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Sample records for hyperbranched polymers capable

  1. Randomly Hyperbranched Polymers

    NASA Astrophysics Data System (ADS)

    Konkolewicz, Dominik; Gilbert, Robert G.; Gray-Weale, Angus

    2007-06-01

    We describe a model for the structures of randomly hyperbranched polymers in solution, and find a logarithmic growth of radius with polymer mass. We include segmental overcrowding, which puts an upper limit on the density. The model is tested against simulations, against data on amylopectin, a major component of starch, on glycogen, and on polyglycerols. For samples of synthetic polyglycerol and glycogen, our model holds well for all the available data. The model reveals higher-level scaling structure in glycogen, related to the β particles seen in electron microscopy.

  2. Thermodynamics of solutions containing hyperbranched polymers

    SciTech Connect

    Mio, C.; Lue, L.; Prausnitz, J.

    1996-12-31

    Vapor-liquid equilibria (VLE) have been obtained for solutions of hyperbranched polymers in chloroform, acetone, cyclohexane, methanol, acetonitrile or n-propylamine in the range 35 to 80{degrees}C. Polymers with different branched structures were studied: star, comb and dendritic polymers. Data interpretation is based on the lattice cluster theory (LCT) of Freed and coworkers. Unlike the Flory-Huggins theory, LCT can predict the effect of molecular architecture on thermodynamic solution properties.

  3. Dynamics of Hyperbranched Polymers under Confinement

    NASA Astrophysics Data System (ADS)

    Androulaki, Krystallenia; Chrissopoulou, Kiriaki; Anastasiadis, Spiros H.; Prevosto, Daniele; Labardi, Massimiliano

    2015-03-01

    The effect of severe confinement on the dynamics of three different generations of hyperbranched polyesters (Boltorns) is investigated by Dielectric Spectroscopy. The polymers are intercalated within the galleries of natural Na+-MMT, thus, forming 1nm polymer films confined between solid walls. The Tg's of the polymers determined by DSC show a clear dependence on the generation whereas the transition is completely suppressed when all the polymer chains are intercalated. The dynamic investigation of the bulk polymers reveals two sub-Tg processes, with similar behavior for the three polymers with the segmental relaxation observed above the Tg of each. For the nanocomposites, where all polymers are severely confined, the dynamics show significant differences compared to that of the bulk polymers. The sub-Tg processes are similar for the three generations but significantly faster and with weaker temperature dependence than those in the bulk. The segmental process appears at temperatures below the bulk polymer Tg, it exhibits an Arrhenius temperature dependence and shows differences for the three generations. A slow process that appears at higher temperatures is due to interfacial polarization. Co-financed by the EU and Greek funds through the Operational Program ``Education and Lifelong Learning'' of the NSRF-Research Funding Program: THALES-Investing in knowledge society through the Eur. Social Fund (MIS 377278) and COST Action MP0902-COINAPO.

  4. Local orientational mobility in regular hyperbranched polymers

    NASA Astrophysics Data System (ADS)

    Dolgushev, Maxim; Markelov, Denis A.; Fürstenberg, Florian; Guérin, Thomas

    2016-07-01

    We study the dynamics of local bond orientation in regular hyperbranched polymers modeled by Vicsek fractals. The local dynamics is investigated through the temporal autocorrelation functions of single bonds and the corresponding relaxation forms of the complex dielectric susceptibility. We show that the dynamic behavior of single segments depends on their remoteness from the periphery rather than on the size of the whole macromolecule. Remarkably, the dynamics of the core segments (which are most remote from the periphery) shows a scaling behavior that differs from the dynamics obtained after structural average. We analyze the most relevant processes of single segment motion and provide an analytic approximation for the corresponding relaxation times. Furthermore, we describe an iterative method to calculate the orientational dynamics in the case of very large macromolecular sizes.

  5. Local orientational mobility in regular hyperbranched polymers.

    PubMed

    Dolgushev, Maxim; Markelov, Denis A; Fürstenberg, Florian; Guérin, Thomas

    2016-07-01

    We study the dynamics of local bond orientation in regular hyperbranched polymers modeled by Vicsek fractals. The local dynamics is investigated through the temporal autocorrelation functions of single bonds and the corresponding relaxation forms of the complex dielectric susceptibility. We show that the dynamic behavior of single segments depends on their remoteness from the periphery rather than on the size of the whole macromolecule. Remarkably, the dynamics of the core segments (which are most remote from the periphery) shows a scaling behavior that differs from the dynamics obtained after structural average. We analyze the most relevant processes of single segment motion and provide an analytic approximation for the corresponding relaxation times. Furthermore, we describe an iterative method to calculate the orientational dynamics in the case of very large macromolecular sizes. PMID:27575171

  6. Synthesis and characterization of a hyper-branched water-soluble β-cyclodextrin polymer.

    PubMed

    Trotta, Francesco; Caldera, Fabrizio; Cavalli, Roberta; Mele, Andrea; Punta, Carlo; Melone, Lucio; Castiglione, Franca; Rossi, Barbara; Ferro, Monica; Crupi, Vincenza; Majolino, Domenico; Venuti, Valentina; Scalarone, Dominique

    2014-01-01

    A new hyper-branched water-soluble polymer was synthesized by reacting β-cyclodextrin with pyromellitic dianhydride beyond the critical conditions that allow the phenomenon of gelation to occur. The molar ratio between the monomers is a crucial parameter that rules the gelation process. Nevertheless, the concentration of monomers in the solvent phase plays a key role as well. Hyper-branched β-cyclodextrin-based polymers were obtained performing the syntheses with excess of solvent and cross-linking agent, and the conditions for critical dilution were determined experimentally. A hyper-branched polymer with very high water solubility was obtained and fully characterized both as for its chemical structure and for its capability to encapsulate substances. Fluorescein was used as probe molecule to test the complexation properties of the new material. PMID:25550720

  7. Multifunctional hyperbranched glycoconjugated polymers based on natural aminoglycosides.

    PubMed

    Chen, Mingsheng; Hu, Mei; Wang, Dali; Wang, Guojian; Zhu, Xinyuan; Yan, Deyue; Sun, Jian

    2012-06-20

    Multifunctional gene vectors with high transfection, low cytotoxicity, and good antitumor and antibacterial activities were prepared from natural aminoglycosides. Through the Michael-addition polymerization of gentamycin and N,N'-methylenebisacrylamide, cationic hyperbranched glycoconjugated polymers were synthesized, and their physical and chemical properties were analyzed by FTIR, (1)H NMR, (13)C NMR, GPC, ζ-potential, and acid-base titration techniques. The cytotoxicity of these hyperbranched glycoconjugated polycations was low because of the hydrolysis of degradable glycosidic and amide linkages in acid conditions. Owing to the presence of various primary, secondary, and tertiary amines in the polymers, hyperbranched glycoconjugated polymers showed high buffering capacity and strong DNA condensation ability, resulting in the high transfection efficiency. In the meantime, due to the introduction of natural aminoglycosides into the polymeric backbone, the resultant hyperbranched glycoconjugated polymers inhibited the growth of cancer cells and bacteria efficiently. Combining the gene transfection, antitumor, and antibacterial abilities together, the multifunctional hyperbranched glycoconjugated polymers based on natural aminoglycosides may play an important role in protecting cancer patients from bacterial infections. PMID:22591322

  8. Stars, dendrimers and hyperbranched polymers: Towards understanding structure-property relationships for single molecule constructs

    SciTech Connect

    Mathias, L.J.; Reichert, V.R.; Carothers, T.W.; Bozen, R.M.

    1993-12-31

    New families of tetrahedral core molecules for synthesizing star and hyperbranched polymers are based on new adamantane derivatives. Four-arm structures have been obtained that are capable of chain extension and thermal conversion to highly crosslinked materials. Hyperbranched and star polymers containing siloxysilane repeat units have also been made through polyaddition hydrosilation reactions with star nodes and A-B monomers or A-B{sub 3} monomers. Terminal functionalization has been demonstrated for a variety of reactive and interactive groups that offer possibilities for use in artificial blood and interfacial microreactors. Combination of rigid tetrahedral cores with start or hyperbranched arms should make available new families of materials for composite synthesis, fiber interphase, formation and impact modification.

  9. Modification of polylactide bioplastic using hyperbranched polymer based nanostructures

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Rahul

    Polylactide (PLA) is the most well known renewable resource based biodegradable polymer. The inherent brittleness and poor processability of PLA pose considerable technical challenges and limit its range of commercial applications. The broad objective of this research was to investigate novel pathways for polylactide modification to enhance its mechanical and rheological properties. The focus of this work was to tailor the architecture of a dendritic hyperbranched polymer (HBP) and study its influence on the mechanical and rheological properties of PLA bioplastic. The hyperbranched polymers under consideration are biodegradable aliphatic hydroxyl-functional hyperbranched polyesters having nanoscale dimensions, unique physical properties and high peripheral functionalities. This work relates to identifying a new and industrially relevant research methodology to develop PLA based nanoblends having outstanding stiffness-toughness balance. In this approach, a hydroxyl functional hyperbranched polymer was crosslinked in-situ with a polyanhydride (PA) in the PLA matrix during melt processing, leading to the generation of new nanoscale hyperbranched polymer based domains in the PLA matrix. Transmission electron microscopy and atomic force microscopy revealed the "sea-island" morphology of PLA-crosslinked HBP blends. The domain size of a large portion of the crosslinked HBP particles in PLA matrix was less than 100 nm. The presence of crosslinked hyperbranched polymers exhibited more than 500% and 800% improvement in the tensile toughness and elongation at break values of PLA, respectively, with a minimal sacrifice of tensile strength and modulus as compared to unmodified PLA. The toughening mechanism of PLA in the presence of crosslinked HBP particles was comprised of shear yielding and crazing. The volume fraction of crosslinked HBP particles and matrix ligament thickness (inter-particle distance) were found to be the critical parameters for the toughening of PLA. The

  10. Bioorthogonal layer-by-layer encapsulation of pancreatic islets via hyperbranched polymers.

    PubMed

    Gattás-Asfura, Kerim M; Stabler, Cherie L

    2013-10-23

    Encapsulation of viable tissues via layer-by-layer polymer assembly provides a versatile platform for cell surface engineering, with nanoscale control over the capsule properties. Herein, we report the development of a hyperbranched polymer-based, ultrathin capsule architecture expressing bioorthogonal functionality and tailored physiochemical properties. Random carbodiimide-based condensation of 3,5-dicarboxyphenyl glycineamide on alginate yielded a highly branched polysaccharide with multiple, spatially restricted, and readily functionalizable terminal carboxylate moieties. Poly(ethylene glycol) (PEG) was utilized to link azido end groups to the structured alginate. Together with a phosphine-functionalized poly(amidoamine) dendrimer, nanoscale layer-by-layer coatings, covalently stabilized via Staudinger ligation, were assembled onto solid surfaces and pancreatic islets. The effects of electrostatic and/or bioorthogonal covalent interlayer interactions on the resulting coating efficiency and stability, as well as pancreatic islet viability and function, were studied. These hyperbranched polymers provide a flexible platform for the formation of covalently stabilized, ultrathin coatings on viable cells and tissues. In addition, the hyperbranched nature of the polymers presents a highly functionalized surface capable of bioorthogonal conjugation of additional bioactive or labeling motifs. PMID:24063764

  11. Diffusion-limited hyperbranched polymers with substitution effect.

    PubMed

    Wang, Long; He, Xuehao; Chen, Yu

    2011-03-14

    Highly branched structure has the essential influence on macromolecular property and functionality in physics and chemistry. In this work, we proposed a diffusion-limited reaction model with the consideration of macromolecular unit relaxations and substitution effect of monomers to study the structure of hyperbranched polymers prepared by slow monomer addition to a core molecule. The exponential relationship (R(g) ∼ N(λ)) between the radius of gyration R(g) and the degree of polymerization N, was systematically analyzed at various branching degrees. It is shown that the effective exponent λ(eff) decreases at lower N and but increases toward that of diffusion-limited aggregation (DLA) clusters (λ(DLA) = 0.4) with the degree of polymerization increasing. The substitution effect of monomers in reaction strongly influences the evolution pathway of λ(eff). With the static light scattering technique, the fractal property of internal chains was further calculated. A general law about the radial distribution of the units of diffusion-limited hyperbranched polymers was found that, at smaller reactivity ratio k(12), the radial density of all monomer units D(A) declines from the center region to the peripheral layer revealing the dense core structure; however, at larger k(12), the density distribution shows a loose-dense-loose structure. These structural characteristics are helpful to deeply understand the property of hyperbranched polymers. PMID:21405187

  12. Hyperbranched polymer stars with Gaussian chain statistics revisited.

    PubMed

    Polińska, P; Gillig, C; Wittmer, J P; Baschnagel, J

    2014-02-01

    Conformational properties of regular dendrimers and more general hyperbranched polymer stars with Gaussian statistics for the spacer chains between branching points are revisited numerically. We investigate the scaling for asymptotically long chains especially for fractal dimensions df = 3 (marginally compact) and df = 2.5 (diffusion limited aggregation). Power-law stars obtained by imposing the number of additional arms per generation are compared to truly self-similar stars. We discuss effects of weak excluded-volume interactions and sketch the regime where the Gaussian approximation should hold in dense solutions and melts for sufficiently large spacer chains. PMID:24574057

  13. Improving of Mechanical and Shape-Memory Properties in Hyperbranched Epoxy Shape-Memory Polymers

    NASA Astrophysics Data System (ADS)

    Santiago, David; Fabregat-Sanjuan, Albert; Ferrando, Francesc; De la Flor, Silvia

    2016-03-01

    A series of shape-memory epoxy polymers were synthesized using an aliphatic amine and two different commercial hyperbranched poly(ethyleneimine)s with different molecular weights as crosslinking agents. Thermal, mechanical, and shape-memory properties in materials modified with different hyperbranched polymers were analyzed and compared in order to establish the effect of the structure and the molecular weight of the hyperbranched polymers used. The presence of hyperbranched polymers led to more heterogeneous networks, and the crosslinking densities of which increase as the hyperbranched polymer content increases. The transition temperatures can be tailored from 56 to 117 °C depending on the molecular weight and content of the hyperbranched polymer. The mechanical properties showed excellent values in all formulations at room temperature and, specially, at T_{g}^{{E^' with stress at break as high as 15 MPa and strain at break as high as 60 %. The shape-memory performances revealed recovery ratios around 95 %, fixity ratios around 97 %, and shape-recovery velocities as high as 22 %/min. The results obtained in this study reveal that hyperbranched polymers with different molecular weights can be used to enhance the thermal and mechanical properties of epoxy-based SMPs while keeping excellent shape-memory properties.

  14. A hyperbranched dopamine-containing PEG-based polymer for the inhibition of α-synuclein fibrillation.

    PubMed

    Breydo, Leonid; Newland, Ben; Zhang, Hong; Rosser, Anne; Werner, Carsten; Uversky, Vladimir N; Wang, Wenxin

    2016-01-22

    Aggregation of α-synuclein is believed to play an important role in Parkinson's disease and in other neurodegenerative maladies. Small molecule inhibitors of this process are among the most promising drug candidates for neurodegenerative diseases. Dendrimers have also been studied for anti-fibrillation applications but they can be difficult and expensive to synthetize. Here we show that RAFT polymerization can be used to produce a hyperbranched polyethylene glycol structure via a one-pot reaction. This polymer included a dopamine moiety, a known inhibitor of α-synuclein fibril formation. Dopamine within the polymer structure was capable of aggregation inhibition, although not to the same degree as free dopamine. This result opens up new avenues for the use of controlled radical polymerizations as a means of preparing hyperbranched polymers for anti-fibrillation activity, but shows that the incorporation of functional groups from known small molecules within polymers may alter their biological activity. PMID:26707645

  15. A hyperbranched dopamine-containing PEG-based polymer for the inhibition of α-synuclein fibrillation

    PubMed Central

    Breydo, Leonid; Newland, Ben; Zhang, Hong; Rosser, Anne; Werner, Carsten; Uversky, Vladimir N.; Wang, Wenxin

    2016-01-01

    Aggregation of α-synuclein is believed to play an important role in Parkinson's disease and in other neurodegenerative maladies. Small molecule inhibitors of this process are among the most promising drug candidates for neurodegenerative diseases. Dendrimers have also been studied for anti-fibrillation applications but they can be difficult and expensive to synthetize. Here we show that RAFT polymerization can be used to produce a hyperbranched polyethylene glycol structure via a one-pot reaction. This polymer included a dopamine moiety, a known inhibitor of α-synuclein fibril formation. Dopamine within the polymer structure was capable of aggregation inhibition, although not to the same degree as free dopamine. This result opens up new avenues for the use of controlled radical polymerizations as a means of preparing hyperbranched polymers for anti-fibrillation activity, but shows that the incorporation of functional groups from known small molecules within polymers may alter their biological activity. PMID:26707645

  16. Hyperbranched chelating polymers for the polymer-assisted ultrafiltration of boric acid

    SciTech Connect

    Smith, B.M.; Todd, P.; Bowman, C.N.

    1999-07-01

    Two hyperbranched chelating polymers, glucoheptonamide derivatives of dendrimetric poly(amido amine) and poly(ethylene imine), were employed in polymer-assisted ultrafiltration and concentration of boron from aqueous feed streams. For feeds containing approximately 1 mM B (10 ppm), volume reduction factors of 20 were observed in cyclic adsorption-desorption. The concentrations of both polymers declined due to permeation through an ultrafiltration membrane with pore sizes which should have retained them. Acid-catalyzed hydrolysis of the amide linkages between the polymer backbone and the chelating side groups is implicated in this loss of polymer mass and effectiveness.

  17. Hyperbranched polymer functional cotton fabric for its in situ deposition of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhang, Desuo; Jiao, Chenlu; Xiong, Jiaqing; Lin, Hong; Chen, Yuyue

    2015-06-01

    This paper describes a strategy of fabricating silver nanoparticles (Ag NPs) finished cotton fabric through in situ synthesis method. In order to endow the cotton fabric with the capability of in situ synthesis of Ag NPs without any other reagents, an amino-terminated hyperbranched polymer (HBP-NH2) was employed to functionalize the cotton fabric. To this end, cotton fabric was oxidized to generate aldehyde groups and then HBP-NH2 was grafted on the oxidized cotton fabric based on the reaction between amino groups and aldehyde groups. Due to numerous imino and amino groups in the polymer and its special three-dimensional structure, the functional cotton fabric could take initiative to capture and reduce silver ions, control the formation of Ag NPs and fix them on the cotton fabric. The sizes of Ag NPs in situ synthesized on cotton fibers range from 4 to 10 nm. The prepared Ag NPs finished cotton fabric has excellent laundering durability.

  18. Spacers' role in the dynamics of hyperbranched polymers

    NASA Astrophysics Data System (ADS)

    Satmarel, C.; von Ferber, C.; Blumen, A.

    2006-05-01

    We investigate hyperbranched polymers (HBPs) and highlight the relation between their architecture and their viscoelastic behavior, while paying special attention to the role of the chainlike spacer segments between branching points. For this we study the dynamics of HBP in solution, based on the generalized Gaussian structure formalism, an extension of the Rouse model, which disregards hydrodynamical and excluded volume effects. For HBP the dynamical effects display, beside the obvious contributions of localized modes on the spacers, also remarkable features, as we highlight based on the exact renormalization procedure recently developed by us in J. Chem. Phys. 123, 034907 (2005). We exemplify these features by analyzing the dynamics of randomly linked star polymers and study the impact both of the length and of the spacers' mobility on the normal modes' spectra. We compute these modes both by numerical diagonalization and also by employing our renormalization procedure; the excellent agreement between these methods allows us to extend the range of investigations to very large HBP.

  19. Synthesis and nonlinear optical properties of a peripherally functionalized hyperbranched polymer by DR1 chromophores.

    PubMed

    Scarpaci, Annabelle; Blart, Errol; Montembault, Véronique; Fontaine, Laurent; Rodriguez, Vincent; Odobel, Fabrice

    2009-08-01

    The first peripheral postfunctionalization of a hyperbranched polyimide by nonlinear optic chromophores (DR1 derivative) was achieved using two different routes. The first one consists in the esterification of the terminal carboxylic acid groups, whereas the second is based on copper-catalyzed Huisgen reaction of the terminal propargylic ester groups. The resulting polymers display good solubility in classical organic solvents and good filmability because thick films can be prepared (up to 2.7 mum). The second-order nonlinear optical properties were measured by SHG at 1064 nm and we show that these hyperbranched polymers exhibit good poling efficiency and good thermal stability since the electro-optic activity remains stable up to 130 degrees C. These results illustrate the potential of hyperbranched polymers to host second-order nonlinear optical chromophores to replace dendrimers or classical linear polymers generally used in this area. PMID:20355797

  20. Hyperbranched Polymers by Type II Photoinitiated Self-Condensing Vinyl Polymerization.

    PubMed

    Aydogan, Cansu; Ciftci, Mustafa; Yagci, Yusuf

    2016-04-01

    Type II photoinitiated self-condensing vinyl polymerization for the preparation of hyperbranched polymers is explored using 2-hydroxyethyl methacrylate (HEMA) or 2-(dimethylamino)ethyl methacrylate (DMAEMA), and methyl methacrylate as hydrogen donating inimers and comonomer, respectively, in the presence of benzophenone and camphorquinone under UV and visible light. Upon irradiation at the corresponding wavelength, the excited photoinitiator abstracts hydrogen from HEMA or DMAEMA leading to the formation of initiating radicals. Depending on the concentration of inimers, type of the photoinitiator, and irradiation time, hyperbranched polymers with different branching densities and cross-linked polymers are formed. PMID:26785924

  1. Preparation of hyperbranched polymer via single electron transfer living radical polymerization

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Chen, X. H.; Li, J.; Cao, X. X.; Cheng, C. J.

    2015-07-01

    α-Trichloromethyl benzyl alcohol is converted to α-trichloromethyl benzyl methacrylate in 62% yield under esterification conditions. The ester proves to be a good inimer to prepare hyperbranched polymer by utilizing SET-LRP approach. The monomer conversion is about 72% at 60°C for 6 h.

  2. A hyperbranched supramolecular polymer constructed by orthogonal triple hydrogen bonding and host-guest interactions.

    PubMed

    Gu, Ruirui; Yao, Jian; Fu, Xin; Zhou, Wei; Qu, Da-Hui

    2015-03-28

    A hyperbranched supramolecular polymer has been constructed through orthogonal self-crosslinking by two classical binding interactions: triple hydrogen bonding interaction between a three-arm melamine derivative and DB24C8-containing bisimide and host-guest interaction between DB24C8 crown ether and ditopic dibenzyl ammonium moieties. PMID:25421931

  3. Metal catalyzed synthesis of hyperbranched ethylene and/or .alpha.-olefin polymers

    DOEpatents

    Sen, Ayusman; Kim, Jang Sub; Pawlow, James H.; Murtuza, Shahid; Kacker, Smita; Wojcinski, III, Louis M.

    2001-01-01

    Oily hyperbranched polymers derived from ethylene, propylene, butene and/or a C.sub.5 -C.sub.24 .alpha.-olefin, and a method for their synthesis, are disclosed. The polymers have non-regular microstructures and are characterized by a ratio ({character pullout})of methyl hydrogens centered around 0.85 ppm on the 1H-NMR spectra of the polymers relative to total aliphatic hydrogens of from about 0.40 to about 0.65 for polymers derived from ethylene or butene, and a ratio ({character pullout})of from greater than 0.50 to about 0.65 for polymers derived from propylene. A method for grafting hyperbranched polymers derived from ethylene, propylene, butene and/or a C.sub.5 -C.sub.24 .alpha.-olefin onto aromatic rings in organic molecules and polymers, and the resulting grafted materials, are also disclosed. The hyperbranched polymers and grafted materials are useful, for example, as lubricants and lubricant additives.

  4. Perfluoroalkyl-Functionalized Hyperbranched Polyglycerol as Pore Forming Agents and Supramolecular Hosts in Polymer Microspheres

    PubMed Central

    Wagner, Olaf; Zieringer, Maximilian; Duncanson, Wynter J.; Weitz, David A.; Haag, Rainer

    2015-01-01

    Perfluoroalkyl-functionalized, hyperbranched polyglycerols that produce stable microbubbles are integrated into a microfluidic emulsion to create porous microspheres. In a previously-presented work a dendrimer with a perfluorinated shell was used. By replacing this dendrimer core with a hyperbranched core and evaluating different core sizes and degrees of fluorinated shell functionalization, we optimized the process to a more convenient synthesis and higher porosities. The new hyperbranched polyglycerol porogens produced more pores and can be used to prepare microspheres with porosity up to 12% (v/v). The presented preparation forms pores with a perfluoroalkyl-functionalized surface that enables the resulting microspheres to act as supramolecular host systems. The microspheres can incorporate gases into the pores and actives in the polymer matrix, while the perfluoroalkylated pore surface can be used to immobilize perfluoro-tagged molecules onto the pores by fluorous-fluorous interaction. PMID:26343631

  5. Perfluoroalkyl-Functionalized Hyperbranched Polyglycerol as Pore Forming Agents and Supramolecular Hosts in Polymer Microspheres.

    PubMed

    Wagner, Olaf; Zieringer, Maximilian; Duncanson, Wynter J; Weitz, David A; Haag, Rainer

    2015-01-01

    Perfluoroalkyl-functionalized, hyperbranched polyglycerols that produce stable microbubbles are integrated into a microfluidic emulsion to create porous microspheres. In a previously-presented work a dendrimer with a perfluorinated shell was used. By replacing this dendrimer core with a hyperbranched core and evaluating different core sizes and degrees of fluorinated shell functionalization, we optimized the process to a more convenient synthesis and higher porosities. The new hyperbranched polyglycerol porogens produced more pores and can be used to prepare microspheres with porosity up to 12% (v/v). The presented preparation forms pores with a perfluoroalkyl-functionalized surface that enables the resulting microspheres to act as supramolecular host systems. The microspheres can incorporate gases into the pores and actives in the polymer matrix, while the perfluoroalkylated pore surface can be used to immobilize perfluoro-tagged molecules onto the pores by fluorous-fluorous interaction. PMID:26343631

  6. Novel functional conjugative hyperbranched polymers with aggregation-induced emission: synthesis through one-pot "A2+B4" polymerization and application as explosive chemsensors and PLEDs.

    PubMed

    Wu, Wenbo; Ye, Shanghui; Yu, Gui; Liu, Yunqi; Qin, Jingui; Li, Zhen

    2012-01-01

    With the aim to develop new tetraphenylethylene (TPE)-based conjugated hyperbranched polymer, TPE units, one famous aggregation-induced emission (AIE) active group, are utilized to construct hyperbranched polymers with three other aromatic blocks, through an "A2+B4" approach by using one-pot Suzuki polycondensation reaction. These three hyperbranched polymers exhibit interesting AIEE behavior and act as explosive chemsensors with high sensitivity both in the nanoparticles and solid states. This is the first report of the AIE activity of the TPE-based conjugated hyperbranched polymers. Their corresponding PLED devices also demonstrate good performance. PMID:22134953

  7. Hyperbranched polymers and dendrimers as templates for organic/inorganic hybrid nanomaterials.

    PubMed

    Huang, Xinhua; Zheng, Sudan; Kim, Il

    2014-02-01

    This paper reviews the recent research and development of hyperbranched polymers (HPs) and dendrimers, and their use as templates for organic-inorganic hybrid nanomaterials. Hyperbranched polymers (HPs) are highly branched macromolecules with three-dimensional globular structures featuring unique properties such as low viscosity, high solubility, and a large number of terminal functional groups compared to their linear analogs. They are easily prepared by (1) condensation polymerization, (2) self-condensing vinyl copolymerization (SCVCP), and (3) ring-opening multibranch polymerization methods. Organic-inorganic hybrid nanomaterials are synthesized by a template approach using HPs/dendrimers. Monometallic, bimetallic (alloy and core/shell), semiconductor, and metal oxide nanoparticles have been prepared by this route. The dendrimer component of these composites serves not only as a template for preparing the nanoparticles but also as a stabilizer for the nanoparticles. PMID:24749446

  8. Broadband optical limiting and nonlinear optical absorption properties of a novel hyperbranched conjugated polymer

    NASA Astrophysics Data System (ADS)

    Li, Chao; Liu, Chunling; Li, Quanshui; Gong, Qihuang

    2004-12-01

    The nonlinear transmittance of a novel hyperbranched conjugated polymer named DMA-HPV has been measured in CHCl 3 solution using a nanosecond optical parametric oscillator. DMA-HPV shows excellent optical limiting performance in the visible region from 490 to 610 nm. An explanation based on the combination of two-photon absorption and reverse saturable absorption was proposed for its huge and broadband nonlinear optical absorption.

  9. Modification of brittle polylactide by novel hyperbranched polymer-based nanostructures.

    PubMed

    Bhardwaj, Rahul; Mohanty, Amar K

    2007-08-01

    The inherent brittleness of polylactide (PLA) poses considerable scientific challenges and limits its large-scale applications. Here, we propose and demonstrate a new industrially relevant methodology to develop a polylactide (PLA)-based nanoblend having outstanding stiffness-toughness balance. In this approach, a hydroxyl functional hyperbranched polymer (HBP) was in-situ cross-linked with a polyanhydride (PA) in the PLA matrix during melt processing. There was formation of new hyperbranched polymer-based cross-linked particles in the PLA matrix. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) revealed the sea-island morphology of PLA-cross-linked HBP blend. The domain size of cross-linked HBP particles in the PLA matrix was less than 100 nm as obtained from TEM. The presence of cross-linked hyperbranched polymer in the PLA matrix exhibited approximately 570% and approximately 847% improvement in the toughness and elongation at break, respectively, as compared to unmodified PLA. The increase in the ductility of modified PLA was related to stress whitening and multiple crazing initiated in the presence of cross-linked HBP particles. Formation of a networked interface as revealed by rheological data was associated with enhanced compatibility of the PLA-cross-linked HBP blend as compared to the PLA/HBP blend. The cross-linking reaction of HBP with PA was confirmed with the help of Fourier transform infrared spectroscopy (FTIR) and low-temperature dynamical mechanical thermal analysis (DMTA). PMID:17605464

  10. Drug complexation, in vitro release and cellular entry of dendrimers and hyperbranched polymers.

    PubMed

    Kolhe, Parag; Misra, Ekta; Kannan, Rangaramanujam M; Kannan, Sujatha; Lieh-Lai, Mary

    2003-06-18

    Highly branched, functionalized polymers have potential to act as efficient drug carrier systems. Dendrimers are ideal candidates among model hyperbranched polymers because of their well-defined structure and high density of functional groups. Using ibuprofen as a model drug, we studied the interaction between the drug and Polyamidoamine (PAMAM) dendrimers (generations 3 and 4 with --NH2 functionality) and Perstrop Polyol (generation 5, hyperbranched polyester with --OH functionality). FTIR and NMR studies suggest that ibuprofen predominantly forms a complex with PAMAM dendrimers because of the ionic interaction between the --NH2 end groups and the carboxyl group of ibuprofen. On an average, up to 78 molecules of ibuprofen could be incorporated into one molecule of PAMAM-G4-NH2 with 64 end groups. This complex is stable in deionized water and methanol. The in vitro release of ibuprofen from drug-dendrimer complex is appreciably slower compared to pure ibuprofen. The complexed drug enters A549 cells much more rapidly than pure drug suggesting that dendrimers may be able to carry the complexed drug inside cells efficiently. Hyperbranched Polyol (with 128 --OH end groups) appears to encapsulate approximately 24 drug molecules. Perhaps the lack of strong interactions between the --OH end groups and the drugs prevents complex formation. PMID:12787643

  11. Enhanced immunogenicity of multivalent MUC1 glycopeptide antitumour vaccines based on hyperbranched polymers.

    PubMed

    Glaffig, M; Palitzsch, B; Stergiou, N; Schüll, C; Strassburger, D; Schmitt, E; Frey, H; Kunz, H

    2015-10-28

    Enhancing the immunogenicity of an antitumour vaccine still poses a major challenge. It depends upon the selected antigen and the mode of its presentation. We here describe a fully synthetic antitumour vaccine, which addresses both aspects. For the antigen, a tumour-associated MUC1 glycopeptide as B-cell epitope was synthesised and linked to the immunostimulating T-cell epitope P2 derived from tetanus toxoid. The MUC1-P2 conjugate is presented multivalently on a hyperbranched polyglycerol to the immune system. In comparison to a related vaccine of lower multivalency, this vaccine exposing more antigen structures on the hyperbranched polymer induced significantly stronger immune responses in mice and elicited IgG antibodies of distinctly higher affinity to epithelial tumour cells. PMID:26299280

  12. A supramolecular hyperbranched polymer based on molecular recognition between benzo-21-crown-7 and secondary ammonium salt.

    PubMed

    Li, Hui; Fan, Xiaodong; Tian, Wei; Zhang, Haitao; Zhang, Wanbin; Yang, Zhen

    2014-12-01

    A novel A2-B3-type supramolecular hyperbranched polymer was prepared based on the benzo-21-crown-7/secondary ammonium salt recognition motif. The resulting supramolecular polymer exhibited a reversible disassembled-assembled process by adding or removing potassium ions. PMID:25315034

  13. Thermally stable hyperbranched polyether-based polymer electrolyte for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Wu, Feng; Feng, Ting; Wu, Chuan; Bai, Ying; Ye, Lin; Chen, Junzheng

    2010-01-01

    A thermally stable polymer matrix, comprising hyperbranched polyether PHEMO (poly(3-{2-[2-(2-hydroxyethoxy) ethoxy] ethoxy}methyl-3'-methyloxetane)) and PVDF-HFP (poly(vinylidene fluoride-hexafluoropropylene)), has been successfully prepared for applications in lithium-ion batteries. This type of polymer electrolyte has been made by adding different amounts of lithium bis(oxalate)borate (LiBOB) to the polymer matrix. Its thermal and structural properties were measured using differential scanning calorimetry and x-ray diffraction. Experimental results show that the polymer electrolyte system possesses good thermal stability, with a decomposition temperature above 420 °C. The ionic conductivity of the polymer electrolyte system is dependent on the lithium salt content, reaching a maximum of 1.1 × 10-5 S cm-1 at 30 °C and 2.3 × 10-4 S cm-1 at 80 °C when doped with 10 wt% LiBOB.

  14. Fully-branched hyperbranched polymers with a diselenide core as glutathione peroxidase mimics.

    PubMed

    Fu, Yu; Chen, Junyi; Xu, Huaping; Van Oosterwijck, Chantal; Zhang, Xi; Dehaen, Wim; Smet, Mario

    2012-05-14

    A novel glutathione peroxidase (GPx) mimic has been prepared by incorporation of a selenium-based catalytic unit into the focal point of a fully-branched hyperbranched polymer. First, an AB(2) monomer consisting of isatin and an electron rich aromatic moiety was polycondensed in the presence of 5-nitroisatin as a core reagent, resulting in a polymer with 100% degree of branching. The latter was coupled to the catalytically active moiety, Br(CH(2))(5) SeSe(CH(2))(5) Br, by nucleophilic substitution of the bromides by the residual amide groups of the incorporated nitroisatin core. The obtained polymer has demonstrated prominent GPx activity as desired, which could be attributed to the hydrophobic, densely branched and core-shell structure of the polymer surrounding the catalytic center. PMID:22434542

  15. Reduction-responsive multifunctional hyperbranched polyaminoglycosides with excellent antibacterial activity, biocompatibility and gene transfection capability.

    PubMed

    Huang, Yajun; Ding, Xiaokang; Qi, Yu; Yu, Bingran; Xu, Fu-Jian

    2016-11-01

    There is an increasing demand in developing of multifunctional materials with good antibacterial activity, biocompatibility and drug/gene delivery capability for next-generation biomedical applications. To achieve this purpose, in this work series of hydroxyl-rich hyperbranched polyaminoglycosides of gentamicin, tobramycin, and neomycin (HP and SS-HP with redox-responsive disulfide bonds) were readily synthesized via ring-opening reactions in a one-pot manner. Both HP and SS-HP exhibit high antibacterial activity toward Escherichia coli and Staphylococcus aureus. Meanwhile, the hemolysis assay of the above materials shows good biocompatibility. Moreover, SS-HPs show excellent gene transfection efficiency in vitro due to the breakdown of reduction-responsive disulfide bonds. For an in vivo anti-tumor assay, the SS-HP/p53 complexes exhibit potent inhibition capability to the growth of tumors. This study provides a promising approach for the design of next-generation multifunctional biomedical materials. PMID:27561884

  16. Preparation and characterization of tablet formulation based on solid dispersion of glimepiride and poly(ester amide) hyperbranched polymer.

    PubMed

    Reven, Sebastjan; Homar, Miha; Peternel, Luka; Kristl, Julijana; Žagar, Ema

    2013-01-01

    The feasibility of incorporating a solid dispersion containing poorly soluble antidiabetic drug glimepiride and poly(ester amide) hyperbranched polymer into a tablet using a direct-compression tabletting technique was investigated. Tablet cores were additionally coated with hydroxypropyl methylcellulose phthalate in order to protect the extremely hygroscopic solid dispersion from atmospheric moisture. Preliminary stability studies show that glimepiride, which is in amorphous form within solid dispersion, is chemically stable, even if tablets are exposed to elevated temperature and/or moisture. In-vitro dissolution studies show some impact of storage conditions on the tablet cores disintegration time and, consequently, drug release rate. Glimepiride solubility also deteriorates somewhat, most probably due to its partial recrystallization. Storage conditions much less affect the physical stability of coated tablets, which was ascribed to reduced tablet hygroscopicity due to the presence of protecting coating. The hyperbranched polymers are rather new and complex macromolecules. Therefore, we addressed also the biocompatibility of hyperbranched polymer, i.e., its impact on haemolysis of the red blood cells. The concentration required for the haemolytic effect on the red blood cells is around 100-times higher than its expected gastrointestinal luminal concentration, which makes the occurrence of hyperbranched polymer mediated cytotoxicity very unlikely. PMID:21812524

  17. SOLUTION RHEOLOGY OF HYPERBRANCHED POLYESTERS AND THEIR BLENDS WITH LINEAR POLYMERS

    EPA Science Inventory

    In this study, the rheological properties of different generations of hyperbranched polyesters in 1-methyl-2-pyrrolidinone solvent and their blends with poly(2-hydroxyethyl methacrylate) have ben investigated. All the hyperbranched polyester solutions exhibited Newtonian behavior...

  18. A supramolecular Janus hyperbranched polymer and its photoresponsive self-assembly of vesicles with narrow size distribution.

    PubMed

    Liu, Yong; Yu, Chunyang; Jin, Haibao; Jiang, Binbin; Zhu, Xinyuan; Zhou, Yongfeng; Lu, Zhongyuan; Yan, Deyue

    2013-03-27

    Herein, we report a novel Janus particle and supramolecular block copolymer consisting of two chemically distinct hyperbranched polymers, which is coined as Janus hyperbranched polymer. It is constructed by the noncovalent coupling between a hydrophobic hyperbranched poly(3-ethyl-3-oxetanemethanol) with an apex of an azobenzene (AZO) group and a hydrophilic hyperbranched polyglycerol with an apex of a β-cyclodextrin (CD) group through the specific AZO/CD host-guest interactions. Such an amphiphilic supramolecular polymer resembles a tree together with its root very well in the architecture and can further self-assemble into unilamellar bilayer vesicles with narrow size distribution, which disassembles reversibly under the irradiation of UV light due to the trans-to-cis isomerization of the AZO groups. In addition, the obtained vesicles could further aggregate into colloidal crystal-like close-packed arrays under freeze-drying conditions. The dynamics and mechanism for the self-assembly of vesicles as well as the bilayer structure have been disclosed by a dissipative particle dynamics simulation. PMID:23464832

  19. Hard and flexible nanocomposite coatings using nanoclay-filled hyperbranched polymers.

    PubMed

    Fogelström, Linda; Malmström, Eva; Johansson, Mats; Hult, Anders

    2010-06-01

    The combination of hardness, scratch resistance, and flexibility is a highly desired feature in many coating applications. The aim of this study is to achieve this through the introduction of an unmodified nanoclay, montmorillonite (Na(+)MMT), in a polymer resin based on the hyperbranched polyester Boltorn H30. Smooth and transparent films were prepared from both the neat and the nanoparticle-filled hyperbranched resins. X-ray diffraction (XRD) and transmission electron microscopy (TEM) corroborated a mainly exfoliated structure in the nanocomposite films, which was also supported by results from dynamic mechanical analysis (DMA). Furthermore, DMA measurements showed a 9-16 degrees C increase in Tg and a higher storage modulus-above and below the T(g)-both indications of a more cross-linked network, for the clay-containing film. Thermogravimetric analysis (TGA) demonstrated the influence of the nanofiller on the thermal properties of the nanocomposites, where a shift upward of the decomposition temperature in oxygen atmosphere is attributed to the improved barrier properties of the nanoparticle-filled materials. Conventional coating characterization methods demonstrated an increase in the surface hardness, scratch resistance and flexibility, with the introduction of clay, and all coatings exhibited excellent chemical resistance and adhesion. PMID:20509674

  20. Covalent layer-by-layer assembly of hyperbranched polymers on alginate microcapsulesto impart stability and permselectivity.

    PubMed

    Gattás-Asfura, Km; Valdes, M; Celik, E; Stabler, Cl

    2014-12-14

    The microencapsulation of cells has shown promise as a therapeutic vehicle for the treatment of a wide variety of diseases. While alginate microcapsules provide an ideal cell encapsulation material, polycations coatings are commonly employed to enhance stability and impart permselectivity. In this study, functionalized hyperbranched alginate and dendrimer polymers were used to generate discreet nanoscale coatings onto alginate microbeads via covalent layer-by-layer assembly. The bioorthogonal Staudinger ligation scheme was used to chemoselectively crosslink azide functionalized hyperbranched alginate (alginate-hN3) to methyl-2-diphenylphosphino-terephthalate (MDT) linked PAMAM dendrimer (PAMAM-MDT). Covalent layer-by-layer deposition of PAMAM-MDT/alginate-hN3 coatings onto alginate microbeads resulted in highly stable coatings, even after the inner alginate gel was liquefied to form microcapsules. The permselectivity of the coated microcapsules could be manipulated via the charge density of the PAMAM, the number of layers deposited, and the length of the functional arms. The cytocompatibility of the resulting PAMAM-MDT/alginate-hN3 coating was evaluated using a beta cell line, with no significant detrimental response observed. The biocompatibility of the coatings in vivo was also found comparable to uncoated alginate beads. The remarkable stability and versatile nature of these coatings provides an appealing option for bioencapsulation and the release of therapeutic agents. PMID:25478165

  1. Metal Coordination Stoichiometry Controlled Formation of Linear and Hyperbranched Supramolecular Polymers.

    PubMed

    Lin, Cuiling; Xu, Luonan; Huang, Libo; Chen, Jia; Liu, Yuanyuan; Ma, Yifan; Ye, Feixiang; Qiu, Huayu; He, Tian; Yin, Shouchun

    2016-09-01

    Controlling the topologies of polymers is a hot topic in polymer chemistry because the physical and/or chemical properties of polymers are determined (at least partially) by their topologies. This study exploits the host-guest interactions between dibenzo-24-crown-8 and secondary ammonium salts and metal coordination interactions between 2,6-bis(benzimidazolyl)-pyridine units with metal ions (Zn(II) and/or Eu(III) ) as orthogonal non-covalent interactions to prepare supramolecular polymers. By changing the ratios of the metal ion additives (Zn(NO3 )2 and Eu(NO3 )3 ) linkers to join the host-guest dimeric complex, the linear supramolecular polymers (100 mol% Zn(NO3 )2 per ligand) and hyperbranched supramolecular polymers (97 mol% Zn(NO3 )2 and 3 mol% Eu(NO3 )3 per ligand) are separately and successfully constructed. This approach not only expands topological control over polymeric systems, but also paves the way for the functionalization of smart and adaptive materials. PMID:27377646

  2. HBP Builder: A Tool to Generate Hyperbranched Polymers and Hyperbranched Multi-Arm Copolymers for Coarse-grained and Fully Atomistic Molecular Simulations

    NASA Astrophysics Data System (ADS)

    Yu, Chunyang; Ma, Li; Li, Shanlong; Tan, Haina; Zhou, Yongfeng; Yan, Deyue

    2016-05-01

    Computer simulation has been becoming a versatile tool that can investigate detailed information from the microscopic scale to the mesoscopic scale. However, the crucial first step of molecular simulation is model building, particularly for hyperbranched polymers (HBPs) and hyperbranched multi-arm copolymers (HBMCs) with complex and various topological structures. Unlike well-defined polymers, not only the molar weight of HBPs/HBMCs with polydispersity, but the HBPs/HBMCs with the same degree of polymerization (DP) and degree of branching (DB) also have many possible topological structures, thus making difficulties for user to build model in molecular simulation. In order to build a bridge between model building and molecular simulation of HBPs and HBMCs, we developed HBP Builder, a C language open source HBPs/HBMCs building toolkit. HBP Builder implements an automated protocol to build various coarse-grained and fully atomistic structures of HBPs/HBMCs according to user’s specific requirements. Meanwhile, coarse-grained and fully atomistic output structures can be directly employed in popular simulation packages, including HOOMD, Tinker and Gromacs. Moreover, HBP Builder has an easy-to-use graphical user interface and the modular architecture, making it easy to extend and reuse it as a part of other program.

  3. HBP Builder: A Tool to Generate Hyperbranched Polymers and Hyperbranched Multi-Arm Copolymers for Coarse-grained and Fully Atomistic Molecular Simulations.

    PubMed

    Yu, Chunyang; Ma, Li; Li, Shanlong; Tan, Haina; Zhou, Yongfeng; Yan, Deyue

    2016-01-01

    Computer simulation has been becoming a versatile tool that can investigate detailed information from the microscopic scale to the mesoscopic scale. However, the crucial first step of molecular simulation is model building, particularly for hyperbranched polymers (HBPs) and hyperbranched multi-arm copolymers (HBMCs) with complex and various topological structures. Unlike well-defined polymers, not only the molar weight of HBPs/HBMCs with polydispersity, but the HBPs/HBMCs with the same degree of polymerization (DP) and degree of branching (DB) also have many possible topological structures, thus making difficulties for user to build model in molecular simulation. In order to build a bridge between model building and molecular simulation of HBPs and HBMCs, we developed HBP Builder, a C language open source HBPs/HBMCs building toolkit. HBP Builder implements an automated protocol to build various coarse-grained and fully atomistic structures of HBPs/HBMCs according to user's specific requirements. Meanwhile, coarse-grained and fully atomistic output structures can be directly employed in popular simulation packages, including HOOMD, Tinker and Gromacs. Moreover, HBP Builder has an easy-to-use graphical user interface and the modular architecture, making it easy to extend and reuse it as a part of other program. PMID:27188541

  4. HBP Builder: A Tool to Generate Hyperbranched Polymers and Hyperbranched Multi-Arm Copolymers for Coarse-grained and Fully Atomistic Molecular Simulations

    PubMed Central

    Yu, Chunyang; Ma, Li; Li, Shanlong; Tan, Haina; Zhou, Yongfeng; Yan, Deyue

    2016-01-01

    Computer simulation has been becoming a versatile tool that can investigate detailed information from the microscopic scale to the mesoscopic scale. However, the crucial first step of molecular simulation is model building, particularly for hyperbranched polymers (HBPs) and hyperbranched multi-arm copolymers (HBMCs) with complex and various topological structures. Unlike well-defined polymers, not only the molar weight of HBPs/HBMCs with polydispersity, but the HBPs/HBMCs with the same degree of polymerization (DP) and degree of branching (DB) also have many possible topological structures, thus making difficulties for user to build model in molecular simulation. In order to build a bridge between model building and molecular simulation of HBPs and HBMCs, we developed HBP Builder, a C language open source HBPs/HBMCs building toolkit. HBP Builder implements an automated protocol to build various coarse-grained and fully atomistic structures of HBPs/HBMCs according to user’s specific requirements. Meanwhile, coarse-grained and fully atomistic output structures can be directly employed in popular simulation packages, including HOOMD, Tinker and Gromacs. Moreover, HBP Builder has an easy-to-use graphical user interface and the modular architecture, making it easy to extend and reuse it as a part of other program. PMID:27188541

  5. High performance hyperbranched polymers for improved processing and mechanical properties in thermoset composites

    NASA Astrophysics Data System (ADS)

    Marsh, Timothy

    Hyperbranched polymers, specifically hyperbranched poly(arylene ether ketone imide)s (HBPAEKI), are here studied as blend additives in thermoset composites to improve processing and ultimate performance properties of the composite. Monomer synthesis for HBPAEKI was further advanced in this work leading to higher yields, fewer reactions, and shorter production times. A five step synthetic method with an overall yield of 12% was reduced to a three step process with an overall yield of 38%. Polymer was synthesized under varying conditions and end group chemistry for use in thermoset blends. NMR characterization allowed for the assignment of chemical shifts in monomer and cataloguing of shifts in polymer for use in future work to characterize degree of branching. Cure kinetics of blends of HBPAEKI are explored through the use of differential scanning calorimetry (DSC) and chemorheology using small angle oscillatory shear. In a phenylethynyl terminated imide oligomer (PETI) thermoset resin, reactive phenylethynyl endcapped PAEKI (PEPAEKI) was found to retard cure while non reactive alkyl endcapped PAEKI was found to accelerate cure in DGEBA/DAH epoxy systems. Minimal effect was seen on early stage blend viscosity. Composite properties tested focused on the effect on bulk fracture and interfacial shear strength. No significant effect was seen in fracture toughness by SENB. XPS was used to verify that PEPAEKI was surface active to DGEBA/DDS epoxy/air interfaces to the complete exclusion of the epoxy at the surface. Evidence was also seen consistent with surface activity in alkyl endcapped PAEKI in DGEBA/DAH systems, although the contrast is much lower. Effect of alkyl endcapped HBPAEKI on interfacial shear strength was examined through the use of t-peel and single fiber fracture (SFF) techniques. In some systems, t-peel indicates a clear improvement in peel force, proportional to the blend concentration. In SFF, interfacial shear strength was found to be equal or slightly

  6. Tyrosine Coupling Creates a Hyperbranched Multivalent Protein Polymer Using Horseradish Peroxidase via Bipolar Conjugation Points.

    PubMed

    Minamihata, Kosuke; Yamaguchi, Sou; Nakajima, Kei; Nagamune, Teruyuki

    2016-05-18

    Protein polymers of covalently cross-linked protein monomers are highly attractive biomaterials because each monomer unit possesses distinct protein functions. Protein polymers often show enhancement effects on the function by integrating a large number of molecules into one macromolecule. The cross-linking site of component proteins should be precisely controlled to avoid diminishing the protein function. However, preparing protein polymers that are cross-linked site-specifically with a high cross-linking degree is a challenge. Here, we demonstrate the preparation of a site-specifically cross-linked protein polymer that has a hyperbranched polymer-like structure with a high cross-linking degree. A horseradish peroxidase (HRP) reaction was used to achieve the protein polymerization through a peptide tag containing a tyrosine residue (Y-tag). Y-tag sequences were introduced to both N- and C-termini of a model protein, protein G. The dual Y-tagged protein G (Y-pG-Y) was treated with HRP to form a Y-pG-Y polymer possessing average and maximum cross-linking degree of approximately 70-mer and 150-mer, respectively. The Y-pG-Y polymer shows the highest cross-linking degree among the protein polymers reported, which are completely soluble in water and cross-linked via covalent bonding. The Y-pG-Y was cross-linked site-specifically at the Tyr residue in the Y-tag, retaining its function, and the Y-pG-Y polymer showed extremely strong avidity against immunoglobulin G. The reactivities of N- and C-terminal Y-tags were evaluated, and we revealed that the difference in the radical formation rate by HRP was the key for yielding highly cross-linked protein polymers. PMID:27093089

  7. Structure and dynamics of hyperbranched polymers in bulk and under nanoscopic confinement

    NASA Astrophysics Data System (ADS)

    Anastasiadis, S. H.; Chrissopoulou, K.; Karatasos, K.; Fotiadou, S.; Karageorgaki, C.; Tanis, I.; Tragoudaras, D.; Frick, B.

    2013-03-01

    The structure and dynamics of a hyperbranched polyesteramide (Hybrane S 1200) and its nanocomposites with natural montmorillonite (Na+-MMT) are investigated. In bulk, the behavior is probed by QENS with MD simulations employed for a deeper insight into the relevant relaxation processes. The energy-resolved elastically scattered intensity from the polymer relaxes with two steps, one below and one above the polymer Tg. The QENS spectra are consistent with the elastic measurements and can be correlated to the results emerging from the detailed description afforded by the atomistic simulations, which cover a broad time range and predict the existence of three relaxation processes. The nanocomposites are investigated by XRD, DSC and QENS. XRD reveals an intercalated nanocomposite structure. The polymer chains confined within the galleries show similarities in the dynamic behavior with that of the bulk polymer for temperatures below the bulk polymer Tg, whereas they exhibit frozen dynamics under confinement at temperatures higher than that. Sponsored by the Greek GSRT (ΣÙ NEP ΓA ΣIA 09 ΣÙ N-42-580).

  8. Glycodendritic structures based on Boltorn hyperbranched polymers and their interactions with Lens culinaris lectin.

    PubMed

    Arce, Eva; Nieto, Pedro M; Díaz, Vicente; Castro, Rossana García; Bernad, Antonio; Rojo, Javier

    2003-01-01

    Multivalent scaffolds bearing carbohydrates have been prepared to mediate biological processes where carbohydrates are involved. These systems consist of dendritic structures based on Boltorn H20 and H30 hyperbranched polymers to which carbohydrates are linked through a convenient spacer. Mannose has been chosen as a sugar unit to test the viability of this strategy. These glycodendritic compounds have been prepared in a few steps with good yields, showing a high solubility in physiological media and low toxicity. The binding of these dendritic polymers to the mannose-binding lectin Lens culinaris (LCA) was studied using STD-NMR experiments and quantitative precipitation assays. The results demonstrate the existence of a clear interaction between the mannose derivative systems and the Lens lectin where the dendritic scaffold does not have an important role in mannose binding but supplies the necessary multivalence for lectin cluster formation. These glycodendritic structures are able to interact with a receptor, and therefore they can be considered as promising tools for biological studies. PMID:12862436

  9. Construction and application of a pH-sensitive nanoreactor via a double-hydrophilic multiarm hyperbranched polymer.

    PubMed

    Zhu, Lijuan; Shi, Yunfeng; Tu, Chunlai; Wang, Ruibing; Pang, Yan; Qiu, Feng; Zhu, Xinyuan; Yan, Deyue; He, Lin; Jin, Chengyu; Zhu, Bangshang

    2010-06-01

    A double-hydrophilic multiarm hyperbranched polymer with a hyperbranched poly(amidoamine) (HPAMAM) core and many poly(ethylene glycol) monomethyl ether (MPEG) arms connected by pH-sensitive acylhydrazone bonds (HPAMAM-g-MPEG) was successfully prepared. Benefiting from the cationic dendritic core and PEGylation shell, the double-hydrophilic multiarm hyperbranched polymer was used as a nanoreactor for CdS quantum dots (CdS QDs) synthesis in aqueous solution. The obtained HPAMAM-g-MPEG and CdS/HPAMAM-g-MPEG nanocomposites were carefully characterized by (1)H NMR, (13)C NMR, Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible absorption spectroscopy (UV-vis), fluorescence spectroscopy (FL), dynamic light scattering (DLS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and electronic dispersive X-ray spectroscopy (EDS) analysis. Both (1)H NMR and fluorescence spectroscopy investigations confirmed that the acylhydrazone linkage between the dendritic core and linear arms was readily broken under acidic condition (pH <5.5). When MPEG arms departed from the HPAMAM core, the fluorescence intensity of CdS/HPAMAM-g-MPEG nanocomposites greatly increased. Such pH-responsive behavior of CdS/HPAMAM-g-MPEG nanocomposites was utilized as an exploration of a novel fluorescence probe in an acidic lysosome exemplified by COS-7 cells. PMID:20225825

  10. Supramolecular self-assembly of amphiphilic hyperbranched polymers at all scales and dimensions: progress, characteristics and perspectives.

    PubMed

    Zhou, Yongfeng; Yan, Deyue

    2009-03-14

    This feature article describes the supramolecular self-assembly of hyperbranched polymers (HBPs), including the progress, unique characteristics and future perspectives. HBPs are irregular in molecular structure compared with that of linear block copolymers and dendrimers. However, similar to these well-defined polymer tectons, HBPs have displayed great potential to be excellent precursors in solution self-assembly, interfacial self-assembly and hybrid self-assembly. Many impressive supramolecular aggregates and hybrids at all scales and dimensions, such as macroscopic tubes, micro- or nano-vesicles, fibers, spherical micelles and honeycomb films, have been generated. In addition, HBPs also demonstrate unique characteristics or advantages in supramolecular self-assembly behaviours, including controllable morphologies and structures, special properties, characteristic self-assembly mechanism and facile functionalization process. Although still being at the early stage, self-assembly of HBPs has provided a new avenue for the development of supramolecular chemistry. PMID:19240868

  11. Polymers with integrated sensing capabilities

    NASA Astrophysics Data System (ADS)

    Kunzelman, Jill Nicole

    This dissertation is focused on the creation and characterization of new types of chromogenic polymers, which change their absorption and/or fluorescence characteristics in response to an external stimulus. These optical sensor materials rely on chromophores that display pronounced color changes upon self-assembly as a result of charge-transfer interactions and/or conformational changes. When these chromophores are incorporated into a polymer of interest, the relative amounts of dispersed and aggregated molecules (and therefore their optical appearance) can be initially tuned by controlling the extent of aggregation via the materials composition and the processing protocol employed; the phase-behavior is changed in a predefined manner upon exposure to a specific stimulus. This sensing scheme was exploited in a number of different polymer matrices, leading to a variety of sensor types including mechanochromic, thermochromic, moisture-sensing, and shape-memory materials that allow visualization of the set/release temperature. Important design fundamentals of "aggregachromic" sensor dyes are discussed and chemical structure is related to type of interactions (hydrophobic, pi-pi, charge-transfer) and self-assembly/color relationships. The knowledge is used to control behavior such as piezochromism, aggregation rate, and intramolecular-excimer-formation.

  12. Development of hyperbranched polymers with non-covalent interactions for extraction and determination of aflatoxins in cereal samples.

    PubMed

    Liu, Xiaoyan; Li, Huihui; Xu, Zhigang; Peng, Jialin; Zhu, Shuqiang; Zhang, Haixia

    2013-10-01

    A novel approach for assembling homogeneous hyperbranched polymers based on non-covalent interactions with aflatoxins was developed; the polymers were used to evaluate the extraction of aflatoxins B1, B2, G1 and G2 (AFB1, AFB2, AFG1 and AFG2) in simulant solutions. The results showed that the extraction efficiencies of three kinds of synthesized polymers for the investigated analytes were not statistically different; as a consequence, one of the representative polymers (polymer I) was used as the solid-phase extraction (SPE) sorbent to evaluate the influences of various parameters, such as desorption conditions, pH, ionic strength, concentration of methanol in sample solutions, and the mass of the sorbent on the extraction efficiency. In addition, the extraction efficiencies for these aflatoxins were compared between the investigated polymer and the traditional sorbent C18. The results showed that the investigated polymer had superior extraction efficiencies. Subsequently, the proposed polymer for the SPE packing material was employed to enrich and analyze four aflatoxins in the cereal powder samples. The limits of detection (LODs) at a signal-to-noise (S/N) ratio of 3 were in the range of 0.012-0.120 ng g(-1) for four aflatoxins, and the limits of quantification (LOQs) calculated at S/N=10 were from 0.04 to 0.40 ng g(-1) for four aflatoxins. The recoveries of four aflatoxins from cereal powder samples were in the range of 82.7-103% with relative standard deviations (RSDs) lower than 10%. The results demonstrate the suitability of the SPE approach for the analysis of trace aflatoxins in cereal powder samples. PMID:24050668

  13. Aptamer-Functionalized and Backbone Redox-Responsive Hyperbranched Polymer for Targeted Drug Delivery in Cancer Therapy.

    PubMed

    Zhuang, Yuanyuan; Deng, Hongping; Su, Yue; He, Lin; Wang, Ruibin; Tong, Gangsheng; He, Dannong; Zhu, Xinyuan

    2016-06-13

    A novel type of backbone redox-responsive hyperbranched poly(2-((2-(acryloyloxy)ethyl)disulfanyl)ethyl 4-cyano-4-(((propylthio)carbonothioyl)-thio)-pentanoate-co-poly(ethylene glycol) methacrylate) (HPAEG) has been designed and prepared successfully via the combination of reversible addition-fragmentation chain-transfer (RAFT) polymerization and self-condensing vinyl polymerization (SCVP). Owing to the existence of surface vinyl groups, HPAEG could be efficiently functionalized by DNA aptamer AS1411 via Michael addition reaction to obtain an active tumor targeting drug delivery carrier (HPAEG-AS1411). The amphiphilic HPAEG-AS1411 could form nanoparticles by macromolecular self-assembly strategy. Cell Counting Kit-8 (CCK-8) assay illustrated that HPAEG-AS1411 nanoparticles had low cytotoxicity to normal cell line. Flow cytometry and confocal laser scanning microscopy (CLSM) results demonstrated that HPAEG-AS1411 nanoparticles could be internalized into tumor cells via aptamer-mediated endocytosis. Compared with pure HPAEG nanoparticles, HPAEG-AS1411 nanoparticles displayed enhanced tumor cell uptake. When the HPAEG-AS1411 nanoparticles loaded with anticancer drug doxorubicin (DOX) were internalized into tumor cells, the disulfide bonds in the backbone of HPAEG-AS1411 were cleaved by glutathione (GSH) in the cytoplasm, so that DOX was released rapidly. Therefore, DOX-loaded HPAEG-AS1411 nanoparticles exhibited a high tumor cellular proliferation inhibition rate and low cytotoxicity to normal cells. This aptamer-functionalized and backbone redox-responsive hyperbranched polymer provides a promising platform for targeted drug delivery in cancer therapy. PMID:27113017

  14. Active site formation mechanism of carbon-based oxygen reduction catalysts derived from a hyperbranched iron phthalocyanine polymer

    NASA Astrophysics Data System (ADS)

    Hiraike, Yusuke; Saito, Makoto; Niwa, Hideharu; Kobayashi, Masaki; Harada, Yoshihisa; Oshima, Masaharu; Kim, Jaehong; Nabae, Yuta; Kakimoto, Masa-aki

    2015-04-01

    Carbon-based cathode catalysts derived from a hyperbranched iron phthalocyanine polymer (HB-FePc) were characterized, and their active-site formation mechanism was studied by synchrotron-based spectroscopy. The properties of the HB-FePc catalyst are compared with those of a catalyst with high oxygen reduction reaction (ORR) activity synthesized from a mixture of iron phthalocyanine and phenolic resin (FePc/PhRs). Electrochemical measurements demonstrate that the HB-FePc catalyst does not lose its ORR activity up to 900°C, whereas that of the FePc/PhRs catalyst decreases above 700°C. Hard X-ray photoemission spectra reveal that the HB-FePc catalysts retain more nitrogen components than the FePc/PhRs catalysts between pyrolysis temperatures of 600°C and 800°C. This is because the linked structure of the HB-FePc precursor has high thermostability against nitrogen desorption. Consequently, effective doping of active nitrogen species into the sp 2 carbon network of the HB-FePc catalysts may occur up to 900°C.

  15. Preparation of complementary glycosylated hyperbranched polymer/poly(ethylene glycol) brushes and their selective interactions with hepatocytes.

    PubMed

    Liang, Su; Yu, Shan; Gao, Changyou

    2016-09-01

    Selective cell adhesion and migration, which mimics the natural biological events in vivo, is very important for the right repair of damaged tissues. In this study, glycosylated hyperbranched polymers (LA-HPMA) were synthesized, and were grafted on glass slide through dopamine deposition with different densities adjusted by co-grafting of poly(ethylene glycol) (PEG). The LA-HPMA and PEG molecular brushes were characterized by X-ray photoelectron spectroscopy (XPS), quartz crystal microbalance with dissipation (QCM-d) and ellipsometry. The adhesion of human hepatoma (HepG2) cells was promoted on the surface of a higher LA-HPMA density, and the migration rate was accelerated from 6.4μm/h on PEG surface to 12.7μm/h on 75% LA-HPMA surface. By contrast, the density and spreading area of mouse embryonic fibroblast (NIH3T3) cells were not significantly influenced by the LA-HPMA density, and the migration rate did not change significantly on all types of surfaces either. Therefore, the specific interactions of carbohydrate-protein can be used to modulate cell behaviors in vitro, for example the selective adhesion and migration of HepG2 cells. PMID:27209383

  16. A fast low-temperature micromolding process for hydrophilic microfluidic devices using UV-curable acrylated hyperbranched polymers

    NASA Astrophysics Data System (ADS)

    Jin, Young-Hyun; Cho, Young-Ho; Schmidt, Lars E.; Leterrier, Yves; Månson, Jan-Anders E.

    2007-06-01

    A novel UV-curable low-stress hyperbranched polymer (HBP) micromolding process is presented for the fast and low-temperature fabrication of hydrophilic microfluidic devices. Process, material and surface properties of the acrylated polyether HBP are also characterized and compared to those of polydimethylsiloxane (PDMS) and cyclic olefin copolymers (COC). The HBP dispensed on a PDMS master was cured at room temperature using a 3 min UV exposure at the intensity of 22.2 mW cm-2. Thermal, mechanical and surface properties of the micromolded HBP structures have been characterized and resulted in a glass transition temperature of 55 °C, Young's modulus of 770 MPa and hydrophilic surface having a water contact angle of 54°. Micromolding of 33 µm thick HBP microstructures has been demonstrated. We achieved 14.5 µm wide vertical walls, 14.7 µm wide fluidic channels, 24.1 µm wide square pillars and 53.4 µm wide square holes. A microfluidic network device, composed of microfluidic channels and reservoirs, was fabricated and its microfluidic performance has been verified by a fluidic test.

  17. Sirtuin 1 evaluation with a novel immunoassay approach based on TiO2-Au label and hyperbranched polymer hybrid.

    PubMed

    An, Yarui

    2016-08-15

    Accurate and highly sensitive evaluation of the sirtuin 1 (SirT1) level is becoming increasingly important for understanding the contribution of SirT1 in metabolism pathways. Here, a novel electrochemical immunoassay of SirT1 based on crosslinked hyperbranched azo-polymer decorated with gold colloids (Au-HAP) as sensing platform and titanium dioxide (TiO2)-Au nanocomposites to immobilize secondary antibody-horseradish peroxidase (Ab2-HRP) as electrochemical labels has been designed. Greatly enhanced sensitivity was achieved by exploiting the excellent conductivity of Au nanoparticle, the amplification effect of Au-HAP and TiO2-Au, and the favorable catalytic ability of HRP. The nanocomposites of Au-HAP and TiO2-Au could attach numerous capture antibodies on the surface for significant immune recognition efficiency. Meanwhile, the TiO2-Au-labeled Ab2-HRP using an HRP-thionine-H2O2 (hydrogen peroxide) detection system could further induce signal readout. Under optimal conditions, the signal intensity was linearly related to the concentration of SirT1 in the range of 1-500 ng ml(-1), and the limit of detection was 0.28 ng ml(-1). The developed biosensor exhibits attractive performance for the analysis of SirT1, with rapid response, high sensitivity, and high accuracy, and could become a promising technique for protein detection. PMID:27264194

  18. Hyperbranched polymer mediated fabrication of water soluble carbon nanotube-metal nanoparticle hybrids

    NASA Astrophysics Data System (ADS)

    Li, Haiqing; Cooper-White, Justin J.

    2013-03-01

    1-Pyrenemethanol initiated hyperbranched polyglycerol (PiHP) has been synthesized and utilized to non-covalently functionalize pristine multi-walled carbon nanotubes (CNTs) through π-π stacking interactions. Mediated with the PiHP coating, a variety of metal nanoparticles (Au, Ag, Pd and Pt) were in situ generated and randomly tethered on the CNT sidewalls, producing various water-soluble CNT/PiHP/metal hybrids. Particularly, the resulting CNT/PiHP/Pt hybrids possess improved metal coverage in comparison to the reported CNT/Pt nanohybrids obtained by the use of conventional non-covalent CNT surface-modifiers. Depending on the using concentration of Pt2+ precursor, Pt coverage in CNT/PiHP/Pt hybrids can be effectively controlled. In the meanwhile, Pt component on the CNT sidewalls can be either well isolated nanoparticles or loose ``nanoclusters''. To test the promising catalytic application of these obtained CNT/PiHP/Pt hybrids, a systematic investigation on their catalytic performance towards the reduction of 4-nitrophenol to produce 4-aminophenol was performed. Surprisingly, these hybrids exhibited significantly enhanced catalytic activity compared with the conventionally utilized Au and Ag nanoparticles. Moreover, they can be easily recovered and reused without significant loss in catalytic activity after running 6 circles.

  19. Hyperbranched polymer mediated size-controlled synthesis of gadolinium phosphate nanoparticles: colloidal properties and particle size-dependence on MRI relaxivity

    NASA Astrophysics Data System (ADS)

    Frangville, Camille; Gallois, Maylis; Li, Yichen; Nguyen, Hong Hanh; Lauth-de Viguerie, Nancy; Talham, Daniel R.; Mingotaud, Christophe; Marty, Jean-Daniel

    2016-02-01

    Hyperbranched polymers based on the poly(amidoamine), HyPAM, were used to synthesize gadolinium phosphate nanowires under mild conditions. Control of the average particle size was obtained by adjusting polymer concentration. Proton relaxivity measurements reveal an optimum particle size, reaching relaxivity values as high as 55 +/- 9 mM-1 s-1 for r1 and 67 +/- 11 mM-1 s-1 for r2. The colloidal stability of these hybrid systems were optimized through the use of functionalized core-shell polymers containing PEG segments and C18-PEG segments, structures which also offer the possibility of imparting additional function into the polymer-particle hybrids.Hyperbranched polymers based on the poly(amidoamine), HyPAM, were used to synthesize gadolinium phosphate nanowires under mild conditions. Control of the average particle size was obtained by adjusting polymer concentration. Proton relaxivity measurements reveal an optimum particle size, reaching relaxivity values as high as 55 +/- 9 mM-1 s-1 for r1 and 67 +/- 11 mM-1 s-1 for r2. The colloidal stability of these hybrid systems were optimized through the use of functionalized core-shell polymers containing PEG segments and C18-PEG segments, structures which also offer the possibility of imparting additional function into the polymer-particle hybrids. Electronic supplementary information (ESI) available: NMR spectra and integrations versus gadolinium concentration; TEM pictures and corresponding sizes with size dispersions for GdPO4/HyPAM and functionalized core-shell hybrids; EDS elemental mapping measurement; relaxation rate plots; DLS correlogram for NaCl addition; Nile Red fluorescence excitation and emission spectra, cytotoxicity. See DOI: 10.1039/c5nr05064b

  20. Synthesis and Mechanism Insight of a Peptide-Grafted Hyperbranched Polymer Nanosheet with Weak Positive Charges but Excellent Intrinsically Antibacterial Efficacy.

    PubMed

    Gao, Jingyi; Wang, Mingzhi; Wang, Fangyingkai; Du, Jianzhong

    2016-06-13

    Antimicrobial resistance is an increasingly problematic issue in the world and there is a present and urgent need to develop new antimicrobial therapies without drug resistance. Antibacterial polymers are less susceptible to drug resistance but they are prone to inducing serious side effects due to high positive charge. Herein we report a peptide-grafted hyperbranched polymer which can self-assemble into unusual nanosheets with highly effective intrinsically antibacterial activity but weak positive charges (+ 6.1 mV). The hyperbranched polymer was synthesized by sequential Michael addition-based thiol-ene and free radical mediated thiol-ene reactions, and followed by ring-opening polymerization of N-carboxyanhydrides (NCAs). The nanosheet structure was confirmed by transmission electron microscopy (TEM) and atomic force microscopy (AFM) studies. Furthermore, a novel "wrapping and penetrating" antibacterial mechanism of the nanosheets was revealed by TEM and it is the key to significantly decrease the positive charges but have a very low minimum inhibitory concentration (MIC) of 16 μg mL(-1) against typical Gram-positive and Gram-negative bacteria. Overall, our synthetic strategy demonstrates a new insight for synthesizing antibacterial nanomaterials with weak positive charges. Moreover, the unique antibacterial mechanism of our nanosheets may be extended for designing next-generation antibacterial agents without drug resistance. PMID:27181113

  1. Site-selective metallization of polymeric substrates by the hyperbranched polymer templates

    NASA Astrophysics Data System (ADS)

    Li, Peiyuan; Yang, Fang; Li, Xiangcheng; He, Chunling; Su, Wei; Chen, Jinhao; Huo, Lini; Chen, Rui; Lu, Chensheng; Liang, Lifang

    2013-09-01

    We demonstrate a simple, cost-effective and universal technique for the fabrication of copper circuit pattern on flexible polymeric substrate. This method relies on a ternary polyethylenimine-poly(acrylic acid)-substrate film incorporating palladium catalysts, which are used as adhesive interlayers for the copper metallization of flexible polymeric substrates. We demonstrated the fabrication of patterned copper films on a variety of flexible polymers with minimum feature sizes of 200 μm. And the resulting copper circuit showed strong adhesion with underlying flexible polymeric substrates. The films were characterized by ATR FT-IR, contact angle, XPS, XRD, TEM and SEM. The direct patterning of metallic circuit on flexible polymeric substrate indicates great potential for the use in electronics industry.

  2. Impedimetric Aptasensor for Ochratoxin A Determination Based on Au Nanoparticles Stabilized with Hyper-Branched Polymer

    PubMed Central

    Evtugyn, Gennady; Porfireva, Anna; Stepanova, Veronika; Kutyreva, Marianna; Gataulina, Alfiya; Ulakhovich, Nikolay; Evtugyn, Vladimir; Hianik, Tibor

    2013-01-01

    An impedimetric aptasensor for ochratoxin A (OTA) detection has been developed on the base of a gold electrode covered with a new modifier consisting of electropolymerized Neutral Red and a mixture of Au nanoparticles suspended in the dendrimeric polymer Botlorn H30®. Thiolated aptamer specific to OTA was covalently attached to Au nanoparticles via Au-S bonding. The interaction of the aptamer with OTA induced the conformational switch of the aptamer from linear to guanine quadruplex form followed by consolidation of the surface layer and an increase of the charge transfer resistance. The aptasensor makes it possible to detect from 0.1 to 100 nM of OTA (limit of detection: 0.02 nM) in the presence of at least 50 fold excess of ochratoxin B. The applicability of the aptasensor for real sample assay was confirmed by testing spiked beer samples. The recovery of 2 nM OTA was found to be 70% for light beer and 78% for dark beer. PMID:24287535

  3. Preparation of anion-exchangeable polymer vesicles through the self-assembly of hyperbranched polymeric ionic liquids.

    PubMed

    Fan, Yujiao; Zhang, Dapeng; Wang, Jie; Jin, Haibao; Zhou, Yongfeng; Yan, Deyue

    2015-04-28

    This work reports the self-assembly of anion-exchangeable vesicles from an amphiphilic hyperbranched polymeric ionic liquid (HBPIL). By a simple one-step anion exchange with methyl orange, the obtained HBPILs could self-assemble into pH-indicative and colorful vesicles in water with color changes directly visible to the naked eye in response to solution pH. In addition, by another step of anion exchange with bovine serum albumin (BSA), the BSA-coated vesicles could also be readily prepared. PMID:25813408

  4. In situ preparation of fluorescent CdTe quantum dots with small thiols and hyperbranched polymers as co-stabilizers

    PubMed Central

    2014-01-01

    A new strategy for in situ preparation of highly fluorescent CdTe quantum dots (QDs) with 3-mercaptopropionic acid (MPA) and hyperbranched poly(amidoamine)s (HPAMAM) as co-stabilizers was proposed in this paper. MPA and HPAMAM were added in turn to coordinate Cd2+. After adding NaHTe and further microwave irradiation, fluorescent CdTe QDs stabilized by MPA and HPAMAM were obtained. Such a strategy avoids the aftertreatment of thiol-stabilized QDs in their bioapplication and provides an opportunity for direct biomedical use of QDs due to the existence of biocompatible HPAMAM. The resulting CdTe QDs combine the mechanical, biocompatibility properties of HPAMAM and the optical, electrical properties of CdTe QDs together. PMID:24636234

  5. Dynamic Relaxational Behaviour of Hyperbranched Polyether Polyols

    NASA Astrophysics Data System (ADS)

    Navarro-Gorris, A.; Garcia-Bernabé, A.; Stiriba, S.-E.

    2008-08-01

    Hyperbranched polymers are highly cascade branched polymers easily accessible via one-pot procedure from ABm type monomers. A key property of hyperbranched polymers is their molecular architecture, which allows core-shell morphology to be manipulated for further specific applications in material and medical sciences. Since the discovery of hyperbranched polymer materials, an increasing number of reports have been published describing synthetic procedures and technological applications of such materials, but their physical properties have remained less studied until the last decade. In the present work, different esterified hyperbranched polyglycerols have been prepared starting from polyglycerol precursors in presence of acetic acid, thus generating functionalization degree with range from 0 to 94%. Thermal analysis of the obtained samples has been studied by Differential Scanning Calorimetry (DSC). Dielectric Spectroscopy measurements have been analyzed by combining loss spectra deconvolution with the modulus formalism. In this regard, all acetylated polyglycerols exhibited a main relaxation related to the glass transition (α process) and two sub-glassy relaxations (β and γ processes) which vanish at high functionalization degrees.

  6. Conjugation of cytochrome c with ferrocene-terminated hyperbranched polymer and its influence on protein structure, conformation and function

    NASA Astrophysics Data System (ADS)

    Xiao, Fengjuan; Yue, Lin; Li, Song; Li, Xinxin

    2016-06-01

    Interaction mechanism of a new hyperbranched polyurethane-based ferrocene (HPU-Fc) with cytochrome c (cyt c) and cyt c structure and conformation change induced by HPU-Fc were investigated using cyclic voltammogram(CV), differential pulse voltammetry (DPV), circular dichroism (CD), fluorescence, synchronous fluorescence and absorbance spectroscopy technique. The peroxidase activity of cyt c in the presence of HPU-Fc was also studied. The structure and conformation of protein are relatively stable at moderate concentration of HPU-Fc without obvious perturbation of the heme pocket and significant changes in protein secondary structure. Conjugation of cyt c with excessive HPU-Fc (over about 3 times of cyt c) slightly changed the α-helix structure in protein, disturbed the microenvironment around heme as well as away from the heme crevice, which caused the changes of the electrochemical behavior and the absorption spectra. Reasonable amount of HPU-Fc has no significant influence on the protein enzymatic activity, while excess HPU-Fc may cause a conformation not suitable for H2O2 activation and guaiacol oxidation. The interaction of HPU-Fc with cyt c and the conservation of protein function at suitable HPU-Fc amount make prepared complex promising for the synergistic anticancer therapy. CV curves of 10 μM HPU-Fc, 10 μM cyt c and HPU-Fc/cyt c complex (n HPU-Fc: n cyt c = 3.5:1) in 0.5 M KCl (versus SCE) at a sweep rate of 100 mV ṡ s- 1 (b). Interaction mechanism of a new hyperbranched polyurethane-based ferrocene (HPU-Fc) with cytochrome c (cyt c) and cyt c structure and conformation change induced by HPU-Fc were investigated. The structure and conformation of protein are relatively stable at moderate concentration of HPU-Fc. Conjugation of cyt c with excessive HPU-Fc (over about 3 times of cyt c) slightly changed the α-helix structure in protein, disturbed the microenvironment around heme as well as away from the heme crevice, which caused the changes of the

  7. Conjugation of cytochrome c with ferrocene-terminated hyperbranched polymer and its influence on protein structure, conformation and function.

    PubMed

    Xiao, Fengjuan; Yue, Lin; Li, Song; Li, Xinxin

    2016-06-01

    Interaction mechanism of a new hyperbranched polyurethane-based ferrocene (HPU-Fc) with cytochrome c (cyt c) and cyt c structure and conformation change induced by HPU-Fc were investigated using cyclic voltammogram(CV), differential pulse voltammetry (DPV), circular dichroism (CD), fluorescence, synchronous fluorescence and absorbance spectroscopy technique. The peroxidase activity of cyt c in the presence of HPU-Fc was also studied. The structure and conformation of protein are relatively stable at moderate concentration of HPU-Fc without obvious perturbation of the heme pocket and significant changes in protein secondary structure. Conjugation of cyt c with excessive HPU-Fc (over about 3 times of cyt c) slightly changed the α-helix structure in protein, disturbed the microenvironment around heme as well as away from the heme crevice, which caused the changes of the electrochemical behavior and the absorption spectra. Reasonable amount of HPU-Fc has no significant influence on the protein enzymatic activity, while excess HPU-Fc may cause a conformation not suitable for H2O2 activation and guaiacol oxidation. The interaction of HPU-Fc with cyt c and the conservation of protein function at suitable HPU-Fc amount make prepared complex promising for the synergistic anticancer therapy. PMID:26978787

  8. Hyper-branched polymer grafting graphene oxide as an effective flame retardant and smoke suppressant for polystyrene.

    PubMed

    Hu, Weizhao; Yu, Bin; Jiang, Shu-Dong; Song, Lei; Hu, Yuan; Wang, Bibo

    2015-12-30

    A well-defined functionalized graphene oxide (FGO) grafted by hyper-branched flame retardant based on N-aminoethyl piperazine and phosphonate derivative was synthesized to reduce flammability and toxicity of polystyrene (PS). The chemical structure, morphological and thermal properties were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetric analysis, respectively. Micro combustion calorimeter and steady state tube furnace were employed to evaluate the heat and non-heat fire hazards of PS nanocomposites. The incorporation of FGO into PS matrix effectively improved the flame retardancy and restrained the toxicity of the volatiles escaped, which is attributed to that the homogeneous dispersion of FGO in the PS matrix enhanced barrier effect that reduced peak heat release rate, total heat release and toxic gas release during combustion. Furthermore, PS-FGO nanocompsites obviously decreased the amount of flammable and toxic volatiles evolved, such as the aromatic compounds, carbonyl compounds, carbon monoxide, indicating suppressed fire hazards of the PS composites. PMID:26151385

  9. 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

  10. Hyperbranched polyglycerols at the biointerface

    NASA Astrophysics Data System (ADS)

    Moore, Eli; Thissen, Helmut; Voelcker, Nicolas H.

    2013-08-01

    The control over biointerfacial interactions is the key to a broad range of biomedical applications, ranging from implantable devices to drug delivery and nanomedicine. In many of these applications, coatings are required that reduce or prevent non-specific interactions with the biological environment, while at the same time presenting specific bioactive signals. Whilst surface coatings based on polymers such as poly(ethylene glycol) (PEG) have been used successfully, many limitations persist in regard to the biocompatibility, stability and functionality of state-of-the-art polymer coatings. Most of these limitations are related to the fact that, typically, linear polymers are used with associated limited chemical functionality. Here, we examine the development of hyperbranched polyglycerols (HPGs) as promising candidates for the replacement of traditional linear polymers, such as the chemically analogous PEG, for the control of biointerfacial interactions. HPGs are highly branched globular molecules that exhibit a high valency, allow easy access to a variety of functionalities and can present biologically active signals. In this review, a comprehensive overview is provided with respect to the history, synthetic strategies, modifications and applications of HPGs.

  11. Hyperbranched-hyperbranched polymeric nanoassembly to mediate controllable co-delivery of siRNA and drug for synergistic tumor therapy.

    PubMed

    Jia, Hui-Zhen; Zhang, Wei; Zhu, Jun-Yi; Yang, Bin; Chen, Si; Chen, Gang; Zhao, Yi-Fang; Feng, Jun; Zhang, Xian-Zheng

    2015-10-28

    This study reported a flexible nanoplatform constructed on the pH-dependent self-assembly of two kinds of hyperbranched polymers, and then validated its potency as the controllable siRNA/drug co-delivery vehicle for the combination of chemotherapy with RNA interfering (RNAi) therapy. By virtue of pH-reversible phenylboronate linking, phenylboronic acid-tethered hyperbranched oligoethylenimine (OEI600-PBA) and 1,3-diol-rich hyperbranched polyglycerol (HBPO) can be spontaneously interlinked together into a core-corona nanoconstruction. The special buildup of compactly clustering OEI600-PBA units around hydrophobic HBPO aggregate offered significant advantages over parent OEI600-PBA, including strengthened affinity to siRNA, ability of further loading anticancer drug, easier cellular transport, and acidity-responsive release of payloads. To evaluate the co-delivery capability, Beclin1 siRNA and antitumor DOX were used as the therapeutic models in order to suppress the post-chemotherapy survival of tumor cells caused by drug-induced autophagy. The nanoassembly-mediated single delivery of DOX displayed even better anticancer effects than free DOX, demonstrating the superiority of our pH-responsive nano-design. The nanoassembly-mediated co-delivery of siRNA together with DOX can effectively silence Beclin1 gene, suppress DOX-induced autophagy, and consequently provide strong synergism with a significant enhancement of cell-killing effects in cultured cancerous cells. The in vivo combinational treatment was shown to make the tumor more sensitive to DOX chemotherapy while displaying substantially improved safety as compared with the monochemotherapy. PMID:26272764

  12. PEG based hyperbranched polymeric hollow nanospheres

    NASA Astrophysics Data System (ADS)

    Cao, Hongliang; Dong, Yixiao; O'Rorke, Suzanne; Wang, Wenxin; Pandit, Abhay

    2011-02-01

    The synthesis of a new PEG based hyperbranched copolymer of poly(ethylene glycol) methyl ether methacrylate-co-ethylene glycol dimethacrylate (PEGMEMA-co-EGDMA) was achieved via a one-step in situ deactivation enhanced atom transfer radical polymerization (DE-ATRP). Then, hollow PEG based nanospheres were fabricated from this polymer using a solvent evaporation method and post-stabilisation strategy. Furthermore, the analysis using a cellular metabolic activity assay proved that the copolymer did not affect cellular metabolism, indicating that this PEG based polymeric nanosphere has potential for use in drug delivery applications.

  13. Linear-g-hyperbranched and cyclodextrin-based amphiphilic block copolymer as a multifunctional nanocarrier.

    PubMed

    Zhao, Yamei; Tian, Wei; Yang, Guang; Fan, Xiaodong

    2014-01-01

    In this paper, a novel, multifunctional polymer nanocarrier was designed to provide adequate volume for high drug loading, to afford a multiregion encapsulation ability, and to achieve controlled drug release. An amphiphilic, triblock polymer (ABC) with hyperbranched polycarbonsilane (HBPCSi) and β-cyclodextrin (β-CD) moieties were first synthesized by the combination of a two-step reversible addition-fragmentation transfer polymerization into a pseudo-one-step hydrosilylation and quaternization reaction. The ABC then self-assembled into stable micelles with a core-shell structure in aqueous solution. These resulting micelles are multifunctional nanocarriers which possess higher drug loading capability due to the introduction of HBPCSi segments and β-CD moieties, and exhibit controlled drug release based on the diffusion release mechanism. The novel multifunctional nanocarrier may be applicable to produce highly efficient and specialized delivery systems for drugs, genes, and diagnostic agents. PMID:25550733

  14. Patterning of hyperbranched resist materials by e-beam

    NASA Astrophysics Data System (ADS)

    Trimble, Alexander R.; Tully, David C.; Frechet, Jean M. J.; Medeiros, David R.; Angelopoulos, Marie

    2000-06-01

    The application of a hyperbranched polymer with its globular architecture as a chemically amplified resist system is demonstrated. These hyperbranched poly(esters) based on 3,5- dihydroxybenzoic acid and 4,4-bis(4-hydroxyphenyl)valeric acid and obtained by a polycondensation process at high temperatures. Once obtained, the hyperbranched polymers are functionalized with acid and thermally labile t-BOC groups by reaction of their phenolic groups with di-t-butyl dicarbonate in the presence of a catalytic amount of potassium t-butoxide. These globular materials have number average molecular weights (Mn) in the range of 5,000 - 20,000 with polydispersities of 1.5 - 2. Exposure of the hyperbranched resist material formulated with a photoacid generator was carried out using a direct-write electron-beam (e-beam) tool operating at 50 keV with doses of 15 - 40 (mu) C/cm2. Development of these resist materials can be accomplished in either aqueous base developer or organic solvent, thereby allowing access to both the positive and negative tone images. Feature sizes of 100 nm are readily obtained from these unoptimized materials.

  15. Electroactive Polymers as Artificial Muscles: Capabilities, Potentials and Challenges

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph

    2000-01-01

    The low density and the relative ease of shaping made polymers highly attractive materials and they are increasingly being chosen for aerospace applications. Polymer matrix composite materials significantly impacted the construction of high performance aircraft components and structures. In recent years, the resilience characteristics of polymers made them attractive to the emerging field of inflatable structures. Balloons were used to cushion the deployment of the Mars Pathfinder lander on July 4, 1997, paving the way for the recent large number of related initiatives. Inflatable structures are now being used to construct a rover, aerial vehicles, telescopes, radar antennas, and others. Some of these applications have reached space flight experiments, whereas others are now at advanced stages of development.

  16. Electro-optic polymer waveguide grating with fast tuning capability.

    PubMed

    Wang, Yi-Ping; Chen, Jian-Ping; Li, Xin-Wan; Zhou, Jun-He; Shen, Hao; Zhang, Xiao-Hong; Ye, Ai-Lun

    2005-06-10

    A novel fast tunable electro-optic (EO) polymer waveguide grating is proposed and designed. Its resonant wavelength can be linearly tuned via the first-order EO effect with a high sensitivity of 6.1 pm/V. We find that the spectrum characteristics of EO polymer waveguide gratings depend strongly on many grating parameters, such as refractive-index modulation, modulation function, grating period, and period number. Material selection, fabrication technology, EO tuning ability, and polarization dependence of EO polymer waveguide gratings are also discussed. Such a waveguide grating not only overcomes the disadvantages of fiber-optic gratings, such as slow wavelength tuning ability and large-scale integration inconvenience, but also has many advantages, such as high resonant-wavelength tuning sensitivity, the same fabrication technology used for semiconductors, and polarization independence. PMID:16007840

  17. Self-healing hyperbranched poly(aroyltriazole)s

    PubMed Central

    Wei, Qiang; Wang, Jian; Shen, Xiaoyuan; Zhang, Xiao A.; Sun, Jing Zhi; Qin, Anjun; Tang, Ben Zhong

    2013-01-01

    The research on self-healing polymers has been a hot topic. The encapsulated-monomer/catalyst, supramolecular self-assembly, and reversible or dynamic covalent bond formation are the prevailingly adopted strategies. The alternative of irreversible covalent bond formation is, however, to be further developed. In this contribution, self-healing hyperbranched poly(aroyltriazole)s of PI and PII sharing such mechanism were developed. The polymers were synthesized by our developed metal-free click polymerizations of bis(aroylacetylene)s and triazide. They are processible and have excellent film-forming ability. High quality homogeneous films and sticks free from defects could be obtained by casting. The scratched films could be self-repaired upon general heating. The cut films and sticks could be healed by stacking or pressing the halves together at elevated temperature. Thus, these hyperbranched polymers could find broad applications in diverse areas, and our design concept for self-healing materials should be generally applicable to other hyperbranched polymers with reactive groups on their peripheries.

  18. Aliphatic hyperbranched polyester: A new building block in the construction of multifunctional nanoparticles and nanocomposites**

    PubMed Central

    Santra, Santimukul; Kaittanis, Charalambos; Perez, J. Manuel

    2009-01-01

    Herein we report the design and synthesis of multifunctional hyperbranched polyester-based nanoparticles and nanocomposites with properties ranging from magnetic, fluorescence, antioxidant and X-ray contrast. The fabrication of these nanostructures was achieved using a novel aliphatic and biodegradable hyperbranched polyester (HBPE) synthesized from readily available diethylmalonate. The polymer’s globular structure with functional surface carboxylic groups and hydrophobic cavities residing in the polymer’s interior allows for the formation of multifunctional polymeric nanoparticles, which are able to encapsulate a diversity of hydrophobic cargos. Via simple surface chemistry modifications, the surface carboxylic acid groups were modified to yield nanoparticles with a variety of surface functionalizations, such as amino, azide and propargyl groups, which mediated the conjugation of small molecules. This capability achieved the engineering of the HBPE nanoparticle surface for specific cell internalization studies and the formation of nanoparticle assemblies for the creation of novel nanocomposites that retained, and in some cases enhanced, the properties of the parental nanoparticle building blocks. Considering these results, the HBPE polymer, nanoparticles and composites should be ideal for biomedical, pharmaceutical, nanophotonics and material applications. PMID:19957939

  19. A general and efficient method for decorating graphene sheets with metal nanoparticles based on the non-covalently functionalized graphene sheets with hyperbranched polymers.

    PubMed

    Li, Haiqing; Han, Lina; Cooper-White, Justin J; Kim, Il

    2012-02-21

    Multipyrene terminated hyperbranched polyglycidol (mPHP) has been synthesized and used to non-covalently functionalize pristine graphene sheets (GSs) through π-π stacking interactions. Mediated by the mPHP layer, a variety of metal nanoparticles (Au, Ag and Pt) were in situ generated and deposited onto the surface-modified GS, yielding versatile GS/mPHP/metal nanohybrids. As typical examples, by simply controlling the concentration of HAuCl(4) used, Au nanostructures ranging from isolated spheres to a continuous film were created and coated onto the surface-modified GS. The studies on the fluorescence properties of resulting GS/mPHP/Au hybrid nanostructures reveal that the GS and controllable content of Au components in the hybrids can effectively quench the fluorescence emission of mPHP in a controlled manner. Further investigation indicates that GS/mPHP/Au hybrids are promising surface enhanced Raman scattering (SERS) substrates. The SERS activities of these hybrids depend on the contents and form of the Au. The GS/mPHP/Au hybrid containing continuous Au films exhibits the strongest SERS activity. GS/mPHP/Au hybrids are also used as efficient heterogeneous catalysts for the reduction of 4-NP, and demonstrate excellent catalytic performance. The detailed reaction kinetics and the reusability of such catalysts have also been investigated. PMID:22278595

  20. Hyperbranched lead selenide nanowire networks.

    PubMed

    Zhu, Jia; Peng, Hailin; Chan, Candace K; Jarausch, Konrad; Zhang, Xiao Feng; Cui, Yi

    2007-04-01

    Lead chalcogenide nanostructures are good potential candidates for applications in multiexciton solar cells, infrared photodetectors, and electroluminescence devices. Here we report the synthesis and electrical measurements of hyperbranched PbSe nanowire networks. Hyperbranched PbSe nanowire networks are synthesized via a vapor-liquid-solid (VLS) mechanism. The branching is induced by continuously feeding the PbSe reactant with the vapor of a low-melting-point metal catalyst including In, Ga, and Bi. The branches show very regular orientation relationships: either perpendicular or parallel to each other. The diameter of the individual NWs depends on the size of the catalyst droplets, which can be controlled by the catalyst vapor pressure. Significantly, the hyperbranched networks can be grown epitaxially on NaCl, a low-cost substrate for future device array applications. Electrical measurements across branched NWs show the evolution of charge carrier transport with distance and degree of branching. PMID:17348716

  1. Hyperbranched Polycarbosilanes via Nucleophilic Substitution Reactions

    NASA Astrophysics Data System (ADS)

    Interrante, L.; Shen, Q.

    Nucleophilic substitution reactions involving organomagnesium (Grignard) [1] and organolithium reagents have been used extensively for many years to form Si—C bonds (see Reaction Scheme 12.1). However, their use for the construction of hyperbranched polymers whose backbone contains, as a major structural component, silicon—carbon bonds, i.e., polycarbosilanes [2] is relatively more recent. (12.1) begin{array}{l} {{R}}_3 {{SiX + MR'}} to {{R}}_3 {{SiR' + MX}} \\ left({{{R,R' = alkyl}} {{or aryl;}} {{M = Mg(X),}} {{Li,}} {{Na}};{{X = halogen, OR''}}} right) \\ This chapter focuses on the application of such nucleophilic substitution reactions toward the synthesis of hyperbranched polycarbosilanes, with particular emphasis on those preparations that have resulted in relatively well characterized products. These syntheses are organized by the type of ABn monomer unit used (see Section 1.2), where A and B refer to the (C)X and (Si)Xn, respectively, functional ends of the monomer unit and where the nature of the coupling reaction leads to entirely or primarily Si—C bond formation. In most cases, these are “one-pot” reactions that employ monomers that bear halogen or alkoxy groups on the C and Si ends of the unit. Indeed, hyperbranched polycarbosilanes have been described, in general, as “obtained in one synthetic step via a random, one-pot polymerization of multifunctional monomers of AB n type” [2]. Treatment of the ABn monomer with either elemental Mg or an organolithium reagent, ideally (but not always) forms a complexed carbanion (the nucleophile) by reaction with the C-X end of the monomer unit, resulting in an intermediate of the type, (XxM)CSiXn, where M = Mg or Li, X = halogen or alkoxy, and x = 1 (Mg) or 0 (Li). Self-coupling of this reagent via reactions of the type shown in Reaction Scheme 12.1 leads to oligomeric and polymeric products that are connected primarily through Si—C bonds and yield an inorganic MXx by-product.

  2. The Lewis-acid-catalyzed synthesis of hyperbranched poly(glycerol-diacid)s in toluene

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The first examples of monomeric glycerol-derived hyperbranched polyesters produced in a non-polar solvent system are reported here. The polymers were made by the Lewis acid (dibutyltin(IV)oxide)-catalyzed polycondensation of glycerol with either succinic acid (n (aliphatic chain length)=2), glutari...

  3. Degree of branching in hyperbranched poly(glycerol-co-diacid)s synthesized in toluene

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hyperbranched polymers were synthesized by using a Lewis acid (dibutyltin(IV)oxide) to catalyze the polycondensation of glycerol with either succinic acid (n (aliphatic chain length)=2), glutaric acid (n=3) or azelaic acid (n=7) in toluene. These are the first examples of diacid-glycerol hyperbranc...

  4. Water-soluble sulfonated hyperbranched poly(arylene oxindole) catalysts as functional biomimics of cellulases.

    PubMed

    Yu, Feng; Smet, Mario; Dehaen, Wim; Sels, Bert F

    2016-02-14

    A new polymer acid catalyst, sulfonated hyperbranched poly(arylene oxindole), 5-OH-SHPAO, was prepared for selective cellulose hydrolysis. Its superior catalysis, showing high glucose selectivity at almost full cellulose conversion, is attributed to the presence of an hydroxyl group next to the sulfonic acid, therefore mimicking the separate acid-base pair in the cellulase active site. PMID:26759837

  5. Hyper-branched anion exchange membranes with high conductivity and chemical stability.

    PubMed

    Ge, Qianqian; Liu, Yazhi; Yang, Zhengjin; Wu, Bin; Hu, Min; Liu, Xiaohe; Hou, Jianqiu; Xu, Tongwen

    2016-08-01

    In the manuscript, we report the design and preparation of hyper-branched polymer electrolytes intended for alkaline anion exchange membrane fuel cells. The resulting membrane exhibits high conductivity, lower water swelling and shows prolonged chemical stability under alkaline conditions. PMID:27456659

  6. Photoluminescence of Conjugated Star Polymers

    NASA Astrophysics Data System (ADS)

    Ferguson, J. B.; Prigodin, N. V.; Epstein, A. J.; Wang, F.

    2000-10-01

    Higher dimensionality "star" polymers provide new properties beyond those found in their linear analogs. They have been used to improving electronic properties for nonlinear optics through exciton transfer and molecular antenna structures for example (M. Kawa, J. M. J. Frechet, Chem. Mater. 10, 286 (1998).). We report on photoluminescence properties of star polymers with a hyperbranched core (both hyperbranched phenlyene and hyperbranched triphenylamine) and polyhexylthiophene arms. The arm is a conjugated oligomer of polythiophene that has been investigated extensively for metallic like conductivity when doped as well as utilized in field effect transistors in its undoped form (A. Tsumara, H. Koezuka, T. Ando, Appl. Phys. Lett. 49, 1210 (1986).). The cores are respectively, a nonconjugated polymer in the case of hyperbranched phenlyene and a conjugated polymer in the case of hyperbranched triphenylamine. The photoluminesce spectrum (λ_max at 575 nm) is identical for both star polymers with the two electronically different hyperbranched cores and for linear polythiophene alone. We conclude the wave functions of the core and arms do not strongly interact to form states different from their individual states and excitons formed on the hyperbranched cores migrate to the lower bandgap polythiophene before recombining.

  7. Synthesis and Characterization of Degradable Bioconjugated Hydrogels with Hyperbranched Multifunctional Crosslinkers

    PubMed Central

    Pedrón, Sara; Peinado, Carmen; Bosch, Paula; S.Anseth, Kristi

    2010-01-01

    Hyperbranched poly(ester amide) polymer (Hybrane™ S1200; Mn 1200 g/mol) was functionalized with maleic anhydride (MA) and propylene sulfide, to obtain multifunctional crosslinkers with fumaric and thiol-end groups, S1200MA and S1200SH, respectively. The degree of substitution of maleic acid groups (DS) was controlled by varying the molar ratio of MA to S1200 in the reaction mixture. Hydrogels were obtained by UV crosslinking of functionalized S1200 and poly(ethyleneglycol) diacrylate (PEGDA) in aqueous solutions. Compressive modulus increased with decreasing the S1200/PEG ratio and also depended on the DS of the multifunctional crosslinker (S1200). Also, heparin-based macromonomers together with functionalized hyperbranched polymers were used to construct novel functional hydrogels. The multivalent hyperbranched polymers allowed high crosslinking densities in heparin modified gels while introducing biodegradation sites. Both heparin presence and acrylate/thiol ratio have an impact on degradation profiles and morphologies. Hyperbranched crosslinked hydrogels showed no evidence of cell toxicity. Overall, the multifunctional crosslinkers afford hydrogels with promising properties that suggest that these may be suitable for tissue engineering applications. PMID:20561601

  8. Production of CaCO3/hyperbranched polyglycidol hybrid films using spray-coating technique.

    PubMed

    Malinova, Kalina; Gunesch, Manfred; Montero Pancera, Sabrina; Wengeler, Robert; Rieger, Bernhard; Volkmer, Dirk

    2012-05-15

    Biomineralizing organisms employ macromolecules and cellular processing strategies in order to produce highly complex composite materials such as nacre. Bionic approaches translating this knowledge into viable technical production schemes for a large-scale production of biomimetic hybrid materials have met with limited success so far. Investigations presented here thus focus on the production of CaCO(3)/polymer hybrid coatings that can be applied to huge surface areas via reactive spray-coating. Technical requirements for simplicity and cost efficiency include a straightforward one-pot synthesis of low molecular weight hyperbranched polyglycidols (polyethers of 2,3-epoxy-1-propanol) as a simple mimic of biological macromolecules. Polymers functionalized with phosphate monoester, sulfate or carboxylate groups provide a means of controlling CaCO(3) particle density and morphology in the final coatings. We employ reactive spray-coating techniques to generate CaCO(3)/hybrid coatings among which vaterite composites can be prepared in the presence of sulfate-containing hyperbranched polyglycidol. These coatings show high stability and remained unchanged for periods longer than 9 months. By employing carboxylate-based hyperbranched polyglycidol, it is possible to deposit vaterite-calcite composites, whereas phosphate-ester-based hyperbranched polyglycidol leads to calcite composites. Nanoindentation was used to study mechanical properties, showing that coatings thus obtained are slightly harder than pure calcite. PMID:22386308

  9. Vegetable Oil-Based Hyperbranched Thermosetting Polyurethane/Clay Nanocomposites

    PubMed Central

    2009-01-01

    The highly branched polyurethanes and vegetable oil-based polymer nanocomposites have been showing fruitful advantages across a spectrum of potential field of applications.Mesua ferreaL. seed oil-based hyperbranched polyurethane (HBPU)/clay nanocomposites were prepared at different dose levels by in situ polymerization technique. The performances of epoxy-cured thermosetting nanocomposites are reported for the first time. The partially exfoliated structure of clay layers was confirmed by XRD and TEM. FTIR spectra indicate the presence of H bonding between nanoclay and the polymer matrix. The present investigation outlines the significant improvement of tensile strength, scratch hardness, thermostability, water vapor permeability, and adhesive strength without much influencing impact resistance, bending, and elongation at break of the nanocomposites compared to pristine HBPU thermoset. An increment of two times the tensile strength, 6 °C of melting point, and 111 °C of thermo-stability were achieved by the formation of nanocomposites. An excellent shape recovery of about 96–99% was observed for the nanocomposites. Thus, the formation of partially exfoliated clay/vegetable oil-based hyperbranched polyurethane nanocomposites significantly improved the performance. PMID:20596546

  10. Sensing and actuating capabilities of a shape memory polymer composite integrated with hybrid filler

    NASA Astrophysics Data System (ADS)

    Lu, Haibao; Yu, Kai; Liu, Yanju; Leng, Jinsong

    2010-06-01

    In this paper, hybrid fillers, including carbon black (CB) and chopped short carbon fibers (SCF), are integrated into a styrene-based shape memory polymer (SMP) with sensing and actuating capabilities. The hybrid filler is expected to transform insulating SMP into conducting. Static mechanical properties of the SMP composites containing various filler concentrations of hybrid filler reinforcement are studied first, and it is theoretically and experimentally confirmed that the mechanical properties are significantly improved by a factor of filler content of SCF. The excellent electrical properties of this novel type of SMP composite are determined by a four-point-probe method. As a consequence, the sensing properties of SMP composite filled with 5 wt% CB and 2 wt% SCF are characterized by functions of temperature and strain. These two experimental results both aid the use of SMP composites as sensors that respond to changes in temperature or mechanical loads. On the other hand, the actuating capability of SMP composites is also validated and demonstrated. The dynamic mechanical analysis result reveals that the output strength of SMP composites is improved with an increase in filler content of SCF. The actuating capability of SMP composites is subsequently demonstrated in a series of photographs.

  11. Unimolecular micelles based on hydrophobically derivatized hyperbranched polyglycerols: ligand binding properties.

    PubMed

    Kainthan, Rajesh Kumar; Mugabe, Clement; Burt, Helen M; Brooks, Donald E

    2008-03-01

    This paper discusses the binding and release properties of hydrophobically modified hyperbranched polyglycerol-polyethylene glycol copolymers that were originally developed as human serum albumin (HSA) substitutes. Their unimolecular micellar nature in aqueous solution has been proven by size measurements and other spectroscopic methods. These polymers aggregate weakly in solution, but the aggregates are broken down by low shear forces or by encapsulating a hydrophobic ligand within the polymer. The small molecule binding properties of these polymers are compared with those of HSA. The preliminary in vitro paclitaxel release studies showed very promising sustained drug release characteristics achieved by these unimolecular micelles. PMID:18247528

  12. Smart fiber-reinforced polymer rods featuring improved ductility and health monitoring capabilities

    NASA Astrophysics Data System (ADS)

    Belarbi, Abdeldjelil; Watkins, Steve E.; Chandrashekhara, K.; Corra, Josh; Konz, Bethany

    2001-06-01

    The strain-measuring capability of fiber optic strain gages in fiber-reinforced polymer (FRP) rebars was investigated for failure-inducing loads. Fiber optic interferometric sensors were embedded in a pultruded carbon fiber core and then another layer of carbon fibers were filament wound around the core to form a shell. Pultrusion and filament winding techniques protect the fiber optic strain gages from the concrete environment while providing a secure bond to the core and additional ductility to the overall FRP rebar. Tests of coupon FRP rebar and of FRP-rebar-reinforced concrete beams show that the fiber optic strain gages can read internal strain through failure and can duplicate data from conventional linear variable differential transformers and electrical resistance strain gages. Also, the shell of the FRP rebar inside the concrete beams failed before the rebar core providing pseudo-ductility.

  13. Patterning and biofunctionalization of antifouling hyperbranched polyglycerol coatings.

    PubMed

    Moore, Eli; Delalat, Bahman; Vasani, Roshan; Thissen, Helmut; Voelcker, Nicolas H

    2014-07-14

    We demonstrate the patterned biofunctionalization of antifouling hyperbranched polyglycerol (HPG) coatings on silicon and glass substrates. The ultralow fouling HPG coatings afforded straightforward chemical handles for rapid bioconjugation of amine containing biomolecular species. This was achieved by sodium periodate oxidation of terminal HPG diols to yield reactive aldehyde groups. Patterned microprinting of sodium periodate and cell adhesion mediating cyclic peptides containing the RGD sequence resulted in an array of covalently immobilized bioactive signals. When incubated with mouse fibroblasts, the HPG background resisted cell attachment whereas high density cell attachment was observed on the peptide spots, resulting in high-contrast cell microarrays. We also demonstrated single-step, in situ functionalization of the HPG coatings by printing periodate and peptide concurrently. Our results demonstrate the effectiveness of antifouling and functionalized HPG graft polymer coatings and establish their use in microarray applications for the first time. PMID:24956414

  14. Xylanase Immobilized on Novel Multifunctional Hyperbranched Polyglycerol-Grafted Magnetic Nanoparticles: An Efficient and Robust Biocatalyst.

    PubMed

    Landarani-Isfahani, Amir; Taheri-Kafrani, Asghar; Amini, Mina; Mirkhani, Valiollah; Moghadam, Majid; Soozanipour, Asieh; Razmjou, Amir

    2015-08-25

    Although several strategies are now available for immobilization of enzymes to magnetic nanoparticles for bioapplications, little progresses have been reported on the use of dendritic or hyperbranched polymers for the same purpose. Herein, we demonstrated synthesis of magnetic nanoparticles supported hyperbranched polyglycerol (MNP/HPG) and a derivative conjugated with citric acid (MNP/HPG-CA) as unique and convenient nanoplatforms for immobilization of enzymes. Then, an important industrial enzyme, xylanase, was immobilized on the nanocarriers to produce robust biocatalysts. A variety of analytical tools were used to study the morphological, structural, and chemical properties of the biocatalysts. Additionally, the results of biocatalyst systems exhibited the substantial improvement of reactivity, reusability, and stability of xylanase due to this strategy, which might confer them a wider range of applications. PMID:26258956

  15. Synthesis of hyperbranched poly(m-phenylene)s via Suzuki polycondensation of a branched AB2 monomer

    SciTech Connect

    Xue, Zheng; Finke, Aaron D.; Moore, Jeffrey S.

    2010-11-01

    An efficient synthesis of hyperbranched poly(m-phenylene)s is achieved by Suzuki polycondensation of a m-terphenyl-derived branched AB₂ monomer. The resulting hyperbranched polymers show high molecular weight and relatively low polydispersity and are readily soluble in common organic solvents. A catalyst system composed of Pd(OAc)₂ and S-Phos was found to be highly active in the present Suzuki polycondensation protocol. The molecular weight and polydispersity of the polymer are controllable by varying the catalyst loading and the starting monomer concentration. Experimental results are consistent with a pseudo-chain-growth pathway that involves intramolecular catalyst transfer during polymerization. Furthermore, the triflate end groups of the hyperbranched poly(m-phenylene)s can be efficiently converted to other functionalities via in situ Suzuki–Miyaura cross-couplings.

  16. RHEOLOGY OF CONCENTRATED SOLUTIONS OF HYPERBRANCHED POLYESTERS

    EPA Science Inventory

    The solution rheology of different generations of hyperbranched polyesters in N-methyl-2- pyrrolidinone (NMP) solvent was examined in this study. The solutions exhibited Newtonian behavior over a wide range of polyester concentrations. Also, the relative viscosities of poly(amido...

  17. Ductile electroactive biodegradable hyperbranched polylactide copolymers enhancing myoblast differentiation.

    PubMed

    Xie, Meihua; Wang, Ling; Guo, Baolin; Wang, Zhong; Chen, Y Eugene; Ma, Peter X

    2015-12-01

    Myotube formation is crucial to restoring muscular functions, and biomaterials that enhance the myoblast differentiation into myotubes are highly desirable for muscular repair. Here, we report the synthesis of electroactive, ductile, and degradable copolymers and their application in enhancing the differentiation of myoblasts to myotubes. A hyperbranched ductile polylactide (HPLA) was synthesized and then copolymerized with aniline tetramer (AT) to produce a series of electroactive, ductile and degradable copolymers (HPLAAT). The HPLA and HPLAAT showed excellent ductility with strain to failure from 158.9% to 42.7% and modulus from 265.2 to 758.2 MPa. The high electroactivity of the HPLAAT was confirmed by UV spectrometer and cyclic voltammogram measurements. These HPLAAT polymers also showed improved thermal stability and controlled biodegradation rate compared to HPLA. Importantly, when applying these polymers for myotube formation, the HPLAAT significantly improved the proliferation of C2C12 myoblasts in vitro compared to HPLA. Furthermore, these polymers greatly promoted myogenic differentiation of C2C12 cells as measured by quantitative analysis of myotube number, length, diameter, maturation index, and gene expression of MyoD and TNNT. Together, our study shows that these electroactive, ductile and degradable HPLAAT copolymers represent significantly improved biomaterials for muscle tissue engineering compared to HPLA. PMID:26335860

  18. Silicon to Silicone: Stretching the Capabilities of Micromachines with Electroactive Polymers

    NASA Astrophysics Data System (ADS)

    Kornbluh, Roy; Pelrine, Ron; Prahlad, Harsha; Chiba, Seiki

    Electroactive polymer transducers have many features that are desirable for MEMS devices. An especially attractive type of electroactive polymer is dielectric elastomer. Dielectric elastomers, transducers that couple the deformation of a rubbery polymer film to an applied electric field, show particular promise with features such as simple fabrication in a variety of size scales, high strain and energy density, high efficiency and fast speed of response, and inherent flexibility, environmental tolerance, and ruggedness. A variety of actuator configurations has been demonstrated at the small size scales needed for MEMS devices, including rolled “artificial muscle" actuators, framed and bending beam actuators for efficient opto-mechanical switches, and diaphragm and thickness mode actuators for pumps and valves. The performance benefits of electroactive polymers can allow for new generations of devices in microrobotics, communications, and biotechnology. Several challenges remain for electroactive polymers, including microfabrication, integration with driving electronics, and operational lifetime.

  19. Molecular dynamics simulation studies of hyperbranched polyglycerols and their encapsulation behaviors of small drug molecules.

    PubMed

    Yu, Chunyang; Ma, Li; Li, Ke; Li, Shanlong; Liu, Yannan; Zhou, Yongfeng; Yan, Deyue

    2016-08-10

    Hyperbranched polyglycerol (HPG) is one of the most important hyperbranched polymers (HBPs) due to its interesting properties and applications. Herein, the conformation of HPGs depending on the degree of polymerization (DP) and the degree of branching (DB) is investigated explicitly by molecular dynamics simulations. This study shows that the radius of gyration (Rg) scales as Rg ∼ DP(1/3), which is in close agreement with the result of the SANS experiment. For HPGs with the same DP, the radius of gyration, asphericities and solvent accessible surface area all monotonically decrease with the increase of DB; while for HPGs with the same DB, the molecular anisotropy decreases with the increase of DP. The radial density investigation discloses that the cavities are randomly distributed in the interior of the HPG core to support the "dendritic box effect", which can be used to encapsulate the guest molecules. Interestingly, the terminal groups of HPGs with a high Wiener index (WI) are more favorable to fold back into the interiors than those with the low WI when in water. For the hyperbranched multi-arm copolymer with a HPG core and many polyethylene glycol (PEG) arms, drug encapsulation studies show that the PEG caps can not only effectively prevent tamoxifen from leaving the HPG core, but also encapsulate tamoxifen inside the PEG chains. These simulation results have provided more details for understanding the structure-property relationships of HPGs in water. PMID:27465863

  20. Extraordinary Capability for Water Treatment Achieved by a Perfluorous Conjugated Microporous Polymer

    PubMed Central

    Yang, Rui-Xia; Wang, Ting-Ting; Deng, Wei-Qiao

    2015-01-01

    Oils, organic solvents, dyes, and heavy metal ions are primary pollutants in water resources. Currently, no sorbent material can effectively remove these types of pollutants simultaneously. Here we report a perfluorous conjugated microporous polymer with superhydrophobicity and a large surface area, which exhibits outstanding adsorption capacities, kinetics, and recyclability for a wide range of organic solvents, oils, dyes, and heavy metal ions. The adsorption capacities of this polymer, 1376.7 mg g−1 for Congo red, 808.2 mg g−1 for Pb(II) and 303.2 mg g−1 for As(V), are higher than the adsorption capacities of any previously described porous materials. Our theoretical calculation reveals that the superior properties of this polymer are due to fluorination and triple bonds within the polymer. A benchmark experiment indicates that this polymer can efficiently remove these pollutants simultaneously. Application of this polymer may lead to the development of next-generation reusable and portable water purification appliances. PMID:25974738

  1. Extraordinary Capability for Water Treatment Achieved by a Perfluorous Conjugated Microporous Polymer

    NASA Astrophysics Data System (ADS)

    Yang, Rui-Xia; Wang, Ting-Ting; Deng, Wei-Qiao

    2015-05-01

    Oils, organic solvents, dyes, and heavy metal ions are primary pollutants in water resources. Currently, no sorbent material can effectively remove these types of pollutants simultaneously. Here we report a perfluorous conjugated microporous polymer with superhydrophobicity and a large surface area, which exhibits outstanding adsorption capacities, kinetics, and recyclability for a wide range of organic solvents, oils, dyes, and heavy metal ions. The adsorption capacities of this polymer, 1376.7 mg g-1 for Congo red, 808.2 mg g-1 for Pb(II) and 303.2 mg g-1 for As(V), are higher than the adsorption capacities of any previously described porous materials. Our theoretical calculation reveals that the superior properties of this polymer are due to fluorination and triple bonds within the polymer. A benchmark experiment indicates that this polymer can efficiently remove these pollutants simultaneously. Application of this polymer may lead to the development of next-generation reusable and portable water purification appliances.

  2. A highly effective gene delivery vector--hyperbranched poly(2-(dimethylamino)ethyl methacrylate) from in situ deactivation enhanced ATRP.

    PubMed

    Newland, Ben; Tai, Hongyun; Zheng, Yu; Velasco, Diego; Di Luca, Andrea; Howdle, Steven M; Alexander, Cameron; Wang, Wenxin; Pandit, Abhay

    2010-07-14

    A hyperbranched 2-(dimethylamino)ethyl methacrylate (DMAEMA) based polymer has been synthesised by a one-pot in situ deactivation enhanced atom transfer radical polymerisation (DE-ATRP); it exhibits much higher transfection ability than linear poly(DMAEMA) and is comparable to the well known branched poly(ethylene imine) (PEI) and the SuperFect dendrimer but with lower cytotoxicity. PMID:20514386

  3. Prebiotic Alternatives to Proteins: Structure and Function of Hyperbranched Polyesters

    NASA Astrophysics Data System (ADS)

    Mamajanov, Irena; Callahan, Michael P.; Dworkin, Jason P.; Cody, George D.

    2015-06-01

    Proteins are responsible multiple biological functions, such as ligand binding, catalysis, and ion channeling. This functionality is enabled by proteins' three-dimensional structures that require long polypeptides. Since plausibly prebiotic synthesis of functional polypeptides has proven challenging in the laboratory, we propose that these functions may have been initially performed by alternative macromolecular constructs, namely hyperbranched polymers (HBPs), during early stages of chemical evolution. HBPs can be straightforwardly synthesized in one-pot processes, possess globular structures determined by their architecture as opposed to folding in proteins, and have documented ligand binding and catalytic properties. Our initial study focuses on glycerol-citric acid HBPs synthesized via moderate heating in the dry state. The polymerization products consisted of a mixture of isomeric structures of varying molar mass as evidenced by NMR, mass spectrometry and size-exclusion chromatography. Addition of divalent cations during polymerization resulted in increased incorporation of citric acid into the HBPs and the possible formation of cation-oligomer complexes. The chelating properties of citric acid govern the makeup of the resulting polymer, turning the polymerization system into a rudimentary smart material.

  4. Quantitative Assessment of Coumarin-Containing Polymer Film's Capability for Photoalignment of Liquid Crystals

    SciTech Connect

    Kim, C.; Wallace, J.U.; Trajkovska, A.; Ou, J.J.; Chen, S.H.

    2007-12-12

    The photoalignment of a nematic fluid, E-7, and a glassy-nematic oligofluorene, F(MB)5, was investigated on films of Polymers 1 and 2 in the parallel regime. Polarized absorption spectroscopy and computational chemistry were employed to characterize coumarin monomer's and dimer's molar extinction coefficients and to locate absorption dipoles as parallel to their long molecular axes. Moreover, their orientational order parameters, S_m and S_d, were experimentally determined as functions of the extent of dimerization. Higher S_d and Y_d, coumarin dimer's mole fraction, were achieved in films of Polymer 1 than in Polymer 2 because of the greater coumarin mobility of the former. The ability of a coumarin-containing photoalignment film to orient a spin-cast F(MB)5 film was found to improve with increasing Y_d S_d to an extent comparable to that of a rubbed polyimide film. Because of the relatively short lengths of its constituent molecules, E-7 was oriented equally well on both polymer films regardless of the Y_d S_d values.

  5. Probing the molecular design of hyper-branched aryl polyesters towards lubricant applications

    PubMed Central

    Robinson, Joshua W.; Zhou, Yan; Bhattacharya, Priyanka; Erck, Robert; Qu, Jun; Bays, J. Timothy; Cosimbescu, Lelia

    2016-01-01

    We report novel polymeric materials that may be used as viscosity index improvers (VII) for lubricant applications. Our efforts included probing the comb-burst hyper-branched aryl polyester architecture for beneficial viscosity and friction behavior when utilized as an additive in a group I oil. The monomer was designed as to undergo polymerization via polycondensation within the architectural construct (AB2), typical of hyperbranched polymers. The monomer design was comprised of aliphatic arms (12 or 16 methylenes) to provide the necessary lipophilicity to achieve solubility in a non-polar medium. Once polymerized, via catalyst and heat, the surface alcohols were functionalized with fatty acids (lauric and palmitic). Controlling the aliphatic nature of the internal arms and peripheral end-groups provided four unique flexible polymer designs. Changing the reaction time and concentration provided opportunities to investigate the influence of molecular weight and branching density on oil-solubility, viscosity, and friction. Oil-solubility was found to decrease with fewer internal carbons, but the number of internal carbons appears to have little influence on the bulk solution viscosity. At concentrations of 2 wt % in a group I base oil, these polymer additives demonstrated an improved viscosity index and reduced friction coefficient, validating the basic approach. PMID:26727881

  6. Probing the molecular design of hyper-branched aryl polyesters towards lubricant applications.

    PubMed

    Robinson, Joshua W; Zhou, Yan; Bhattacharya, Priyanka; Erck, Robert; Qu, Jun; Bays, J Timothy; Cosimbescu, Lelia

    2016-01-01

    We report novel polymeric materials that may be used as viscosity index improvers (VII) for lubricant applications. Our efforts included probing the comb-burst hyper-branched aryl polyester architecture for beneficial viscosity and friction behavior when utilized as an additive in a group I oil. The monomer was designed as to undergo polymerization via polycondensation within the architectural construct (AB2), typical of hyperbranched polymers. The monomer design was comprised of aliphatic arms (12 or 16 methylenes) to provide the necessary lipophilicity to achieve solubility in a non-polar medium. Once polymerized, via catalyst and heat, the surface alcohols were functionalized with fatty acids (lauric and palmitic). Controlling the aliphatic nature of the internal arms and peripheral end-groups provided four unique flexible polymer designs. Changing the reaction time and concentration provided opportunities to investigate the influence of molecular weight and branching density on oil-solubility, viscosity, and friction. Oil-solubility was found to decrease with fewer internal carbons, but the number of internal carbons appears to have little influence on the bulk solution viscosity. At concentrations of 2 wt % in a group I base oil, these polymer additives demonstrated an improved viscosity index and reduced friction coefficient, validating the basic approach. PMID:26727881

  7. Probing the molecular design of hyper-branched aryl polyesters towards lubricant applications

    NASA Astrophysics Data System (ADS)

    Robinson, Joshua W.; Zhou, Yan; Bhattacharya, Priyanka; Erck, Robert; Qu, Jun; Bays, J. Timothy; Cosimbescu, Lelia

    2016-01-01

    We report novel polymeric materials that may be used as viscosity index improvers (VII) for lubricant applications. Our efforts included probing the comb-burst hyper-branched aryl polyester architecture for beneficial viscosity and friction behavior when utilized as an additive in a group I oil. The monomer was designed as to undergo polymerization via polycondensation within the architectural construct (AB2), typical of hyperbranched polymers. The monomer design was comprised of aliphatic arms (12 or 16 methylenes) to provide the necessary lipophilicity to achieve solubility in a non-polar medium. Once polymerized, via catalyst and heat, the surface alcohols were functionalized with fatty acids (lauric and palmitic). Controlling the aliphatic nature of the internal arms and peripheral end-groups provided four unique flexible polymer designs. Changing the reaction time and concentration provided opportunities to investigate the influence of molecular weight and branching density on oil-solubility, viscosity, and friction. Oil-solubility was found to decrease with fewer internal carbons, but the number of internal carbons appears to have little influence on the bulk solution viscosity. At concentrations of 2 wt % in a group I base oil, these polymer additives demonstrated an improved viscosity index and reduced friction coefficient, validating the basic approach.

  8. Probing the molecular design of hyper-branched aryl polyesters towards lubricant applications

    DOE PAGESBeta

    Robinson, Joshua W.; Zhou, Yan; Bhattacharya, Priyanka; Erck, Robert; Qu, Jun; Bays, J. Timothy; Cosimbescu, Lelia

    2016-01-05

    We report novel polymeric materials that may be used as viscosity index improvers (VII) for lubricant applications. Our efforts included probing the comb-burst hyper-branched aryl polyester architecture for beneficial viscosity and friction behavior when utilized as an additive in a group I oil. The monomer was designed as to undergo polymerization via polycondensation within the architectural construct (AB2), typical of hyperbranched polymers. The monomer design was comprised of aliphatic arms (12 or 16 methylenes) to provide the necessary lipophilicity to achieve solubility in a non-polar medium. Once polymerized, via catalyst and heat, the surface alcohols were functionalized with fatty acidsmore » (lauric and palmitic). Controlling the aliphatic nature of the internal arms and peripheral end-groups provided four unique flexible polymer designs. Changing the reaction time and concentration provided opportunities to investigate the influence of molecular weight and branching density on oil-solubility, viscosity, and friction. Oil-solubility was found to decrease with fewer internal carbons, but the number of internal carbons appears to have little influence on the bulk solution viscosity. Increased branching and degree of polymerization, and thus molecular weight, were found to reduce the solubility of these systems in the base oil. At concentrations of 2 wt % in a group I base oil, these polymer additives demonstrated improved viscosity index and reduced friction coefficient, validating the basic approach.« less

  9. Amphiphilic Hyperbranched Fluoropolymers as Nanoscopic 19F-Magnetic Resonance Imaging Agent Assemblies

    PubMed Central

    Du, Wenjun; Nyström, Andreas M.; Zhang, Lei; Powell, Kenya T.; Li, Yali; Cheng, Chong; Wickline, Samuel A.; Wooley, Karen L.

    2009-01-01

    Three hyperbranched fluoropolymers were synthesized and their micelles were constructed as potential 19F MRI agents. A hyperbranched star-like core was first synthesized via ATR-SCVCP of 4-chloromethyl styrene (CMS), lauryl acrylate (LA) and 1,1,1-tris(4′-(2″-bromoisobutyryloxy)phenyl)ethane (TBBPE). The polymerization gave a small core with Mn of 5.5 kDa with PDI of 1.6, which served as a macroinitiator. Trifluoroethyl methacrylate (TFEMA) and tert-butyl acrylate (tBA) in different ratio were then “grafted” from the core to give three polymers with Mn of ca. 120 kDa and PDI values of ca. 1.6–1.8. After acidolysis of the tert-butyl ester groups, amphiphilic, hyperbranched star-like polymers with Mn of ca. 100 kDa were obtained. These structures were subjected to micelle formation in aqueous solution to give micelles having TEM-measured diameters ranging from 3–8 nm and DLS-measured hydrodynamic diameters from 20–30 nm. These micelles gave a narrow, single resonance by 19F NMR spectroscopy, with a half width of approximately 130 Hz. The T1/T2 parameters were ca. 500 ms and 50 ms, respectively, and were not significantly affected by the composition and sizes of the micelles. 19F MRI phantom images of these fluorinated micelles were acquired, which demonstrated that these fluorinated micelles maybe useful as novel 19F MRI agents for a variety of biomedical studies. PMID:18795785

  10. Photodynamic Therapy With Hyperbranched Poly(Ether-Ester) Chlorin(e6) Nanoparticles On Human Tongue Carcinoma Cal-27 Cells

    PubMed Central

    Li, Pingping; Zhou, Guoyu; Zhu, Xinyuan; Li, Guolin; Yan, Peng; Shen, Linyue; Xu, Qin; Hamblin, Michael R

    2011-01-01

    Background Hyperbranched polymers represent a new class of drug delivery vehicle that can be used to prepare nanoparticles with uniform size distribution. Methods In this study we prepared covalent conjugates between the photosensitizer chlorin(e6) and hyperbranched poly(ether-ester), HPEE. HPEE-ce6 nanoparticles were synthesized by carbodiimide-mediated reaction between HPEE and ce6, and characterized by ultraviolet-visible absorption spectroscopy (UV-Vis), and transmission electron microscopy (TEM). The uptake and phototoxicity of HPEE-ce6 nanoparticles towards human oral tongue cancer CAL-27 cells was detected by confocal laser scanning microscopy (CLSM) and MTT assay respectively. Results The absorption peak of HPEE-ce6 nanoparticles was red-shifted 12-nm compared with ce6, and TEM showed uniform nanoparticles with a diameter of 50-nm. HPEE-ce6 nanoparticles were taken up by CAL-27 cells after 4 hour incubation and localized in the cytoplasm. The MTT assay showed a significantly (P<0.05) higher phototoxicity compared to free ce6 after 12 J/cm2 of 660-nm laser illumination. Conclusions This is the first time to our knowledge that hyperbranched polymers have been used in PDT drug delivery. PMID:22369732

  11. Covalent attachment of a bioactive hyperbranched polymeric layer to titanium surface for the biomimetic growth of calcium phosphates

    PubMed Central

    Tsiourvas, D.; Arkas, M.; Diplas, S.; Mastrogianni, E.

    2010-01-01

    This work is investigating the chemical grafting on Ti surface of a polymer/calcium phosphate coating of improved adhesion for enhanced bioactivity. For this purpose, a whole new methodology was developed based on covalently attaching a hyperbranched poly(ethylene imine) layer on Ti surface able to promote calcium phosphate formation in a next deposition stage. This was achieved through an intermediate surface silanization step. The research included optimization both of the reaction conditions for covalently grafting the intermediate organosilicon and the subsequent hyperbranched poly(ethylene imine) layers, as well as of the conditions for the mechanical and chemical pretreatment of Ti surface before coating. The reaction steps were monitored employing FTIR and XPS analyses, whereas the surface morphology and structure of the successive coating layers were studied by SEM combined with EDS. The analysis confirmed the successful grafting of the hybrid layer which demonstrated very good ability for hydroxyapatite growth in simulated body fluid. PMID:21069559

  12. Carboxymethylated hyperbranched polysaccharide: Synthesis, solution properties, and fabrication of hydrogel.

    PubMed

    Tao, Yongzhen; Zhang, Ruquan; Yang, Wei; Liu, Hongtao; Yang, Hongjun; Zhao, Qinghua

    2015-09-01

    The periphery of hyperbranched polysaccharides has many end groups that can be functioned and used as sites to interact with their surroundings. A water-insoluble hyperbranched β-d-glucan, coded as TM3a, extracted from sclerotia of an edible fungus (Pleurotus tuber-regium), was fractionated and modified chemically to obtain carboxymethylated derivatives (CTM3a). The solution properties of the carboxymethylated polysaccharides were studied systematically in phosphate buffer saline at 37 °C. The results indicated that the carboxymethylated glucans still kept hyperbranched structure after carboxymethylation, and existed as a swollen sphere-like chain conformation. The introduction of carboxymethylated groups permitted the formation of hydrogels through crosslinking CTM3a and silk fibroin with carbodiimide chemistry. The resultant hydrogels with porous and interconnected structure displayed good mechanical and swelling properties. This work provides some valuable and fundamental information of the natural hyperbranched polysaccharide from mushroom for further application in biomedical devices and tissue engineering. PMID:26005154

  13. Hyperbranched Polyglycerol as a Colloid in Cold Organ Preservation Solutions

    PubMed Central

    Gao, Sihai; Guan, Qiunong; Chafeeva, Irina; Brooks, Donald E.; Nguan, Christopher Y. C.; Kizhakkedathu, Jayachandran N.; Du, Caigan

    2015-01-01

    Hydroxyethyl starch (HES) is a common colloid in organ preservation solutions, such as in University of Wisconsin (UW) solution, for preventing graft interstitial edema and cell swelling during cold preservation of donor organs. However, HES has undesirable characteristics, such as high viscosity, causing kidney injury and aggregation of erythrocytes. Hyperbranched polyglycerol (HPG) is a branched compact polymer that has low intrinsic viscosity. This study investigated HPG (MW-0.5 to 119 kDa) as a potential alternative to HES for cold organ preservation. HPG was synthesized by ring-opening multibranching polymerization of glycidol. Both rat myocardiocytes and human endothelial cells were used as an in vitro model, and heart transplantation in mice as an in vivo model. Tissue damage or cell death was determined by both biochemical and histological analysis. HPG polymers were more compact with relatively low polydispersity index than HES in UW solution. Cold preservation of mouse hearts ex vivo in HPG solutions reduced organ damage in comparison to those in HES-based UW solution. Both size and concentration of HPGs contributed to the protection of the donor organs; 1 kDa HPG at 3 wt% solution was superior to HES-based UW solution and other HPGs. Heart transplants preserved with HPG solution (1 kDa, 3%) as compared with those with UW solution had a better functional recovery, less tissue injury and neutrophil infiltration in syngeneic recipients, and survived longer in allogeneic recipients. In cultured myocardiocytes or endothelial cells, significantly more cells survived after cold preservation with the HPG solution than those with the UW solution, which was positively correlated with the maintenance of intracellular adenosine triphosphate and cell membrane fluidity. In conclusion, HPG solution significantly enhanced the protection of hearts or cells during cold storage, suggesting that HPG is a promising colloid for the cold storage of donor organs and cells in

  14. Hyperbranched polyglycerol as a colloid in cold organ preservation solutions.

    PubMed

    Gao, Sihai; Guan, Qiunong; Chafeeva, Irina; Brooks, Donald E; Nguan, Christopher Y C; Kizhakkedathu, Jayachandran N; Du, Caigan

    2015-01-01

    Hydroxyethyl starch (HES) is a common colloid in organ preservation solutions, such as in University of Wisconsin (UW) solution, for preventing graft interstitial edema and cell swelling during cold preservation of donor organs. However, HES has undesirable characteristics, such as high viscosity, causing kidney injury and aggregation of erythrocytes. Hyperbranched polyglycerol (HPG) is a branched compact polymer that has low intrinsic viscosity. This study investigated HPG (MW-0.5 to 119 kDa) as a potential alternative to HES for cold organ preservation. HPG was synthesized by ring-opening multibranching polymerization of glycidol. Both rat myocardiocytes and human endothelial cells were used as an in vitro model, and heart transplantation in mice as an in vivo model. Tissue damage or cell death was determined by both biochemical and histological analysis. HPG polymers were more compact with relatively low polydispersity index than HES in UW solution. Cold preservation of mouse hearts ex vivo in HPG solutions reduced organ damage in comparison to those in HES-based UW solution. Both size and concentration of HPGs contributed to the protection of the donor organs; 1 kDa HPG at 3 wt% solution was superior to HES-based UW solution and other HPGs. Heart transplants preserved with HPG solution (1 kDa, 3%) as compared with those with UW solution had a better functional recovery, less tissue injury and neutrophil infiltration in syngeneic recipients, and survived longer in allogeneic recipients. In cultured myocardiocytes or endothelial cells, significantly more cells survived after cold preservation with the HPG solution than those with the UW solution, which was positively correlated with the maintenance of intracellular adenosine triphosphate and cell membrane fluidity. In conclusion, HPG solution significantly enhanced the protection of hearts or cells during cold storage, suggesting that HPG is a promising colloid for the cold storage of donor organs and cells in

  15. Elastin-Mimetic Protein Polymers Capable of Physical and Chemical Crosslinking

    PubMed Central

    Sallach, Rory E.; Cui, Wanxing; Wen, Jing; Martinez, Adam; Conticello, Vincent P.; Chaikof, Elliot L.

    2008-01-01

    We report the synthesis of a new class of recombinant elastin-mimetic triblock copolymer capable of both physical and chemical crosslinking. These investigations were motivated by a desire to capture features unique to both physical and chemical crosslinking schemes so as to exert optimal control over a wide range of potential properties afforded by protein-based mutiblock materials. We postulated that by chemically locking a multiblock protein assembly in place, functional responses that are linked to specific domain structures and morphologies may be preserved over a broader range of loading conditions that would otherwise disrupt microphase structure solely stabilized by physical crosslinking. Specifically, elastic modulus was enhanced and creep strain reduced through the addition of chemical crosslinking sites. Additionally, we have demonstrated excellent in vivo biocompatibility of glutaraldehyde treated multiblock systems. PMID:18954902

  16. Capability of NIPAM polymer gel in recording dose from the interaction of (10)B and thermal neutron in BNCT.

    PubMed

    Khajeali, Azim; Reza Farajollahi, Ali; Kasesaz, Yaser; Khodadadi, Roghayeh; Khalili, Assef; Naseri, Alireza

    2015-11-01

    The capability of N-isopropylacrylamide (NIPAM) polymer gel to record the dose resulting from boron neutron capture reaction in BNCT was determined. In this regard, three compositions of the gel with different concentrations of (10)B were prepared and exposed to gamma radiation and thermal neutrons. Unlike irradiation with gamma rays, the boron-loaded gels irradiated by neutron exhibited sensitivity enhancement compared with the gels without (10)B. It was also found that the neutron sensitivity of the gel increased by the increase of concentration of (10)B. It can be concluded that NIPAM gel might be suitable for the measurement of the absorbed dose enhancement due to (10)B and thermal neutron reaction in BNCT. PMID:26356043

  17. Controllable Nonspecific Protein Adsorption by Charged Hyperbranched Polyglycerol Thin Films.

    PubMed

    Yu, Yaming; Frey, Holger

    2015-12-01

    Antifouling thin films derived from charged hyperbranched polyglycerol (hbPG) layers were fabricated and evaluated. The anionic hbPG (a-hbPG) monolayers and cationic hbPG/anionic hbPG (c/a-hbPG) bilayers were adsorbed on the underlying self-assembled monolayers (SAMs) of cysteamine and 3-mercaptopropionic acid (3-MPA) by electrostatic interaction, respectively, and their procession was monitored by surface plasmon resonance spectroscopy (SPR). The adsorption of bovine serum albumin (BSA) and fibrinogen on the premade a-hbPG and c/a-hbPG thin films was measured and the capability of these thin films to resist nonspecific protein adsorption was evaluated by SPR as well. It is observed that the c/a-hbPG bilayer films possessed good antifouling properties. With c/a-hbPG bilayers consisting of higher molecular weight a-hbPG, the adsorption of BSA and fibrinogen were as low as 0.015 ng/mm(-2) and 0.0076 ng/mm(-2), respectively, comparable to the traditionally ultralow antifouling surfaces (<0.05 ng/mm(-2) of nonspecific protein adsorption). This work proved that the charged hbPG thin films can strongly reduce the nonspecific protein adsorption and have the promise for the antifouling coatings with improved performance. PMID:26562213

  18. Peroxidase-like activity of gold nanoparticles stabilized by hyperbranched polyglycidol derivatives over a wide pH range.

    PubMed

    Drozd, Marcin; Pietrzak, Mariusz; Parzuchowski, Paweł; Mazurkiewicz-Pawlicka, Marta; Malinowska, Elżbieta

    2015-12-11

    The aim of this work was to carry out comparative studies on the peroxidase-like activity of gold nanoparticles (AuNPs) stabilized with low molecular weight hyperbranched polyglycidol (HBPG-OH) and its derivative modified with maleic acid residues (HBPG-COOH). The influence of the stabilizer to gold precursor ratio on the size and morphology of nanoparticles obtained was checked, and prepared nanoparticles were characterized by means of transmission electron microscopy and UV-Vis spectroscopy. The results indicated the divergent effect of increasing the concentration of stabilizers (HBPG-OH or HBPG-COOH) on the size of the nanostructures obtained. The gold nanoparticles obtained were characterized as having intrinsic peroxidase-like activity and the mechanism of catalysis in acidic and alkaline mediums was consistent with the standard Michaelis-Menten kinetics, revealing a strong affinity of AuNPs with 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 3, 3', 5, 5'-tetramethylbenzidine (TMB), and significantly lower affinity towards phenol. By comparing the kinetic parameters, a negligible effect of polymeric ligand charge on activity against various types of substrates (anionic or cationic) was indicated. The superiority of steric stabilization via the application of tested low-weight hyperbranched polymers over typical stabilizers in preventing salt-induced aggregation and maintaining high catalytic activity in time was proved. The applied hyperbranched stabilizers provide a good tool for manufacturing gold-based nanozymes, which are highly stable and active over a wide pH range. PMID:26567596

  19. Magnetorheological fluids based on a hyperbranched polycarbosilane matrix and iron microparticles

    NASA Astrophysics Data System (ADS)

    Vasiliev, V. G.; Sheremetyeva, N. A.; Buzin, M. I.; Turenko, D. V.; Papkov, V. S.; Klepikov, I. A.; Razumovskaya, I. V.; Muzafarov, A. M.; Kramarenko, E. Yu

    2016-05-01

    Magnetorheological fluids (MFs) based on hyperbranched polycarbosilanes as a carrier medium and micron-sized carbonyl iron particles as filler have been synthesized for the first time. Their magnetorheological (MR) behavior has been studied in steady-state flow regime and under dynamic torsion oscillations on a commercial rheometer. At zero magnetic field, in spite of a rather high molecular mass, the hyperbranched polymers as well as their magnetic compositions with up to 72 mass% of magnetic filler demonstrate Newtonian behavior, and their viscosity considerably increases with magnetic filler content. In magnetic fields MFs show a huge MR response. Namely, in steady-state flow experiments a five orders of magnitude increase in viscosity was observed accompanied by magnetic-field-induced well-pronounced non-Newtonian behavior and a non-zero yield stress. Dynamic experiments demonstrate the transition from liquid-like to solid-like behavior of MFs with a large increase in both the storage and loss moduli under application of a magnetic field. In magnetic fields, the rheological behavior of the obtained MF resembles that of soft MR elastomers being mainly determined by the magnetic particle network formed due to magnetic interactions. In particular, like MR elastomers the MFs exhibit the Payne effect, i.e. dependence of the dynamic modulus on the strain amplitude.

  20. Thermodynamics of coil-hyperbranched poly(styrene-b-acrylated epoxidized soybean oil) block copolymers

    NASA Astrophysics Data System (ADS)

    Lin, Fang-Yi; Hohmann, Austin; Hernández, Nacú; Cochran, Eric

    Here we present the phase behavior of a new type of coil-hyperbranched diblock copolymer: poly(styrene- b-acrylated epoxidized soybean oil), or PS-PAESO. PS-PAESO is an example of a biorenewable thermoplastic elastomer (bio-TPE). To date, we have shown that bio-TPEs can be economical commercial substitutes for their petrochemically derived analogues--such as poly(styrene- b-butadiene- b-styrene) (SBS)--in a range of applications including pressure sensitive adhesives and bitumen modification. From a polymer physics perspective, PS-PAESO is an interesting material in that it couples a linear coil-like block with a highly branched block. Thus in contrast to the past five decades of studies on linear AB diblock copolymers, coil-hyperbranched block copolymers are relatively unknown to the community and can be expected to deviate substantially from the standard ``universal'' phase behavior in the AB systems. To explore these new materials, we have constructed a library of PS-PAESO materials spanning a range of molecular weight and composition values. The phase transition behavior and the morphology information will be interpreted by isochronal temperature scanning in dynamic shear rheology, small angle X-ray scattering and the corresponding transmission electron microscopy.

  1. Reversible hemostatic properties of sulfabetaine/quaternary ammonium modified hyperbranched polyglycerol.

    PubMed

    Wen, Jiying; Weinhart, Marie; Lai, Benjamin; Kizhakkedathu, Jayachandran; Brooks, Donald E

    2016-04-01

    A library of hyperbranched polyglycerols (HPGs) functionalized with different mole fractions of zwitterionic sulfabetaine and cationic quaternary ammonium ligands was synthesized and characterized. A post-polymerization method was employed that utilized double bond moieties on the dendritic HPG for the coupling of thiol-terminated ligands via UV initiated thiol-ene "click" chemistry. The proportions of different ligands were precisely controlled by varying the ligand concentration during the irradiation process. The effect of the polymer library on hemostasis was investigated using whole human blood. It was found that polymer with ≥40% of alkenes converted to positive charges and the remainder to sulfabetaines caused hemagglutination at ≥1 mg/mL, without causing red blood cell lysis. The quaternary ammonium groups can interact with the negative charged sites on the membranes of erythrocytes, which provides the bioadhesion. The zwitterionic sulfabetaine evidently provides a hydration layer to partially mask the adverse effects that are likely to be caused by cationic moieties. The polymer was also found able to enhance platelet aggregation and activation in a concentration and positive charge density-dependent manner, which would contribute to initiating hemostasis. In a variety of other assays the material was found to be largely biocompatible. The polymer-induced hemostasis is obtained by a process independent of the normal blood clotting cascade but dependent on red blood cell agglutination, where the polymers promote hemostasis by linking erythrocytes together to form a lattice to entrap the cells. PMID:26885776

  2. A novel polymer composite as cathode binder of lithium ion batteries with improved rate capability and cyclic stability

    NASA Astrophysics Data System (ADS)

    Fu, Z.; Feng, H. L.; Xiang, X. D.; Rao, M. M.; Wu, W.; Luo, J. C.; Chen, T. T.; Hu, Q. P.; Feng, A. B.; Li, W. S.

    2014-09-01

    In this work, we have developed a novel polymer composite (MPVDF) by embedding maleic anhydride-grated-polyvinylidene fluoride (MA-g-PVDF) into polyvinylidene fluoride (PVDF) as binder of LiCoO2 cathode for lithium ion battery. The cathodes using MPVDF and PVDF as binder have been comparatively investigated with scanning electron microscope (SEM), X-ray diffraction (XRD) and electrochemical measurements. By using MPVDF as the binder for preparing LiCoO2 cathode, the rate capability and cyclic stability of the LiCoO2 cathode in LiCoO2/Artificial graphite battery are improved significantly. Compared to the cathode using PVDF alone, the discharge capacity of the battery increases by 38.5% at 2 C and the capacity retention of the battery is improved from 84.5% to 90.2% after 300 cycles at 0.5 C when the mass ratio of MA-g-PVDF to PVDF in MPVDF binder is 1:4. The improved performance is attributed to the low crystallinity of MPVDF, which allows larger electrolyte uptake. The electrolyte uptake is 43.5% for the LiCoO2 cathode using MPVDF but only 25.3% for the cathode using PVDF alone.

  3. Improvement of extraction capability of magnetic molecularly imprinted polymer beads in aqueous media via dual-phase solvent system.

    PubMed

    Hu, Yuling; Liu, Ruijin; Zhang, Yi; Li, Gongke

    2009-08-15

    In this study, a novel and simple dual-phase solvent system for the improvement of extraction capability of magnetic molecularly imprinted polymer (MIP) beads in aqueous sample was proposed. The method integrated MIP extraction and micro-liquid-liquid extraction (micro-LLE) into only one step. A magnetic MIP beads using atrazine as template was synthesized, and was applied to aqueous media by adding micro-volume of n-hexane to form a co-extraction system. The magnetic MIP beads preferred to suspend in the organic phase, which shielded them from the disturbance of water molecule. The target analytes in the water sample was extracted into the organic phase by micro-LLE and then further bound to the solid-phase of magnetic MIP beads. The beads specificity was significantly improved with the imprinting efficiency of template increasing from 0.5 to 4.4, as compared with that in pure aqueous media. The extraction capacity, equilibration process and cross-selectivity of the MIP dual-phase solvent extraction system were investigated. The proposed method coupled with high-performance liquid chromatography was applied to the analysis of atrazine, simazine, propazine, simetryn, prometryne, ametryn and terbutryn in complicated sample such as tomato, strawberry juice and milk. The method is selective, sensitive and low organic solvent-consuming, and has potential to broaden the range of MIP application in biological and environmental sample. PMID:19576415

  4. Thermoresponsive hyperbranched copolymer with multi acrylate functionality for in situ cross-linkable hyaluronic acid composite semi-IPN hydrogel.

    PubMed

    Dong, Yixiao; Hassan, Waqar; Zheng, Yu; Saeed, Aram Omer; Cao, Hongliang; Tai, Hongyun; Pandit, Abhay; Wang, Wenxin

    2012-01-01

    Thermoresponsive polymers have been widely used for in situ formed hydrogels in drug delivery and tissue engineering as they are easy to handle and their shape can easily conform to tissue defects. However, non-covalent bonding and mechanical weakness of these hydrogels limit their applications. In this study, a physically and chemically in situ cross-linkable hydrogel system was developed from a novel thermoresponsive hyperbranched PEG based copolymer with multi acrylate functionality, which was synthesized via an 'one pot and one step' in situ deactivation enhanced atom transfer radical co-polymerization of poly(ethylene glycol) diacrylate (PEGDA, M(n) = 258 g mol(-1)), poly(ethylene glycol) methyl ether methacrylate (PEGMEMA, M(n )= 475 g mol(-1)) and (2-methoxyethoxy) ethyl methacrylate (MEO(2)MA). This hyperbranched copolymer was tailored to have the lower critical solution temperature to form physical gelation around 37°C. Meanwhile, with high level of acrylate functionalities, a chemically cross-linked gel was formed from this copolymer using thiol functional cross-linker of pentaerythritol tetrakis (3-mercaptopropionate) (QT) via thiol-ene Michael addition reaction. Furthermore, a semi-interpenetrated polymer networks (semi-IPN) structure was developed by combining this polymer with hyaluronic acid (HA), leading to an in situ cross-linkable hydrogel with significantly increased porosity, enhanced swelling behavior and improved cell adhesion and viability both in 2D and 3D cell culture models. PMID:22143908

  5. FRET-capable supramolecular polymers based on a BODIPY-bridged pillar[5]arene dimer with BODIPY guests for mimicking the light-harvesting system of natural photosynthesis.

    PubMed

    Meng, Lu-Bo; Li, Dongqi; Xiong, Shuhan; Hu, Xiao-Yu; Wang, Leyong; Li, Guigen

    2015-03-18

    AA/BB-type and A2/B3-type FRET-capable supramolecular polymers based on a BODIPY-bridged pillar[5]arene dimer and two BODIPY derivative guests have been successfully constructed and their application in mimicking the light-harvesting system of natural photosynthesis was studied. PMID:25690934

  6. Progesterone binding nano-carriers based on hydrophobically modified hyperbranched polyglycerols.

    PubMed

    Alizadeh Noghani, M; Brooks, D E

    2016-03-01

    Progesterone (Pro) is a potent neurosteroid and promotes recovery from moderate Traumatic Brain Injury but its clinical application is severely impeded by its poor water solubility. Here we demonstrate that reversibly binding Pro within hydrophobically modified hyperbranched polyglycerol (HPG-Cn-MPEG) enhances its solubility, stability and bioavailability. Synthesis, characterization and Pro loading into HPG-Cn-MPEG is described. The release kinetics are correlated with structural properties and the results of Differential Scanning Calorimetry studies of a family of HPG-Cn-MPEGs of varying molecular weight and alkylation. While the maximum amount of Pro bound correlates well with the amount of alkyl carbon per molecule contributing to its hydrophobicity, the dominant first order rate constant for Pro release correlates strongly with the amount of structured or bound water in the dendritic domain of the polymer. The results provide evidence to justify more detailed studies of interactions with biological systems, both single cells and in animal models. PMID:26878269

  7. Hybrid Solar Cells with Prescribed Nanoscale Morphologies Based onHyperbranched Semiconductor Nanocrystals

    SciTech Connect

    Gur, Ilan; Fromer, Neil A.; Chen, Chih-Ping; Kanaras, AntoniosG.; Alivisatos, A. Paul

    2006-09-09

    In recent years, the search to develop large-area solar cells at low cost has led to research on photovoltaic (PV) systems based on nanocomposites containing conjugated polymers. These composite films can be synthesized and processed at lower costs and with greater versatility than the solid state inorganic semiconductors that comprise today's solar cells. However, the best nanocomposite solar cells are based on a complex architecture, consisting of a fine blend of interpenetrating and percolating donor and acceptor materials. Cell performance is strongly dependent on blend morphology, and solution-based fabrication techniques often result in uncontrolled and irreproducible blends, whose composite morphologies are difficult to characterize accurately. Here we incorporate 3-dimensional hyper-branched colloidal semiconductor nanocrystals in solution-processed hybrid organic-inorganic solar cells, yielding reproducible and controlled nanoscale morphology.

  8. Surface Grafted Hyper-Branched Polyglycerol Stabilized Ag and AuNPs Heterogeneous Catalysts for Efficient Reduction of Congo Red.

    PubMed

    Murugan, Eagambaram; Shanmugam, Paramasivam

    2016-01-01

    Six types of insoluble polymer-supported beads immobilized with Ag and AuNPs nanoparticle catalysts were synthesized using newly prepared three different types of polymer-supported poly(styrene)-co-poly(vinyl benzene chloride) matrix (PS-PVBC), surface grafted with (i) triethanolamine (TEA), (ii) glycidyl trimethyl ammonium chloride (GTMAC) and (iii) hyper-branched polyglycerol (HPG) and Ag and AuNPs as a catalytic moiety and thus yield polymer-supported nanoparticle catalysts viz., PS-PVBC-TEA-AgNPs and AuNPs, PS-PVBC-g-GTMAC-AgNPs and AuNPs and PS-PVBC-g-GTMAC-AgNPs and AuNPs catalyst respectively. These bead-shaped heterogonous nanoparticle catalysts were characterized by UV-Vis, FTIR, FESEM, HRTEM and TGA techniques. The efficiency for stabilization/loading of metal nanoparticles with respect to varied intensities of hyper-branched chain grafted onto their matrix was screened by determining their comparative catalytic activity. The catalytic potential of these catalysts was inspected through reduction of Congo Red (CR) keeping pseudo first order identical reaction condition. The observed k(obs) values reveal that irrespective of metal the catalyst derived from hyper-branched polyglycerol as stabilizing agent viz., PS-PVBC-g-HPG-AgNPs and PS-PVBC-g-HPG-AuNPs shows (k(obs) = 3.98 x 10⁻² min⁻¹ and k(obs) = 4.54 x 10⁻² min⁻¹) four and two times greater activity than the catalyst derived from TEA and GTMAC hyper-branched chain. Further, for the same reaction PS-PVBC-g-HPG-AuNPs showed more efficiency than the PS-PVBC-g-HPG AgNPs catalyst. The stability and reusability of the superior catalyst viz., PS-PVBC-g-HPG-AuNPs catalyst was observed to be good even at the sixth cycle. This catalyst can be continuously used to conduct the reduction of various dyes in continuous mode operation in industrial scale. PMID:27398471

  9. Negatively charged hyperbranched polyglycerol grafted membranes for osmotic power generation from municipal wastewater.

    PubMed

    Li, Xue; Cai, Tao; Chen, Chunyan; Chung, Tai-Shung

    2016-02-01

    Osmotic power holds great promise as a clean, sustainable and largely unexploited energy resource. Recent membrane development for pressure-retarded osmosis (PRO) is making the osmotic power generation more and more realistic. However, severe performance declines have been observed because the porous layer of PRO membranes is fouled by the feed stream. To overcome it, a negatively charged antifouling PRO hollow fiber membrane has been designed and studied in this work. An antifouling polymer, derived from hyperbranched polyglycerol and functionalized by α-lipoic acid and succinic anhydride, was synthesized and grafted onto the polydopamine (PDA) modified poly(ether sulfone) (PES) hollow fiber membranes. In comparison to unmodified membranes, the charged hyperbranched polyglycerol (CHPG) grafted membrane is much less affected by organic deposition, such as bovine serum albumin (BSA) adsorption, and highly resistant to microbial growths, demonstrated by Escherichia coli adhesion and Staphylococcus aureus attachment. CHPG-g-TFC was also examined in PRO tests using a concentrated wastewater as the feed. Comparing to the plain PES-TFC and non-charged HPG-g-TFC, the newly developed membrane exhibits not only the smallest decline in water flux but also the highest recovery rate. When using 0.81 M NaCl and wastewater as the feed pair in PRO tests at 15 bar, the average power density remains at 5.6 W/m(2) in comparison to an average value of 3.6 W/m(2) for unmodified membranes after four PRO runs. In summary, osmotic power generation may be sustained by properly designing and anchoring the functional polymers to PRO membranes. PMID:26630043

  10. Polymeric assembly of hyperbranched building blocks to establish tunable nanoplatforms for lysosome acidity-responsive gene/drug co-delivery.

    PubMed

    Jia, Hui-Zhen; Zhang, Wei; Wang, Xu-Li; Yang, Bin; Chen, Wei-Hai; Chen, Si; Chen, Gang; Zhao, Yi-Fang; Zhuo, Ren-Xi; Feng, Jun; Zhang, Xian-Zheng

    2015-07-01

    This study plans to develop a nanoparticle technology that can assemble different polymeric "building blocks" with various desired functionalities into one nanosystem in a pH-dependent manner. For this purpose, polymeric building blocks were specifically designed with hyperbranched architectures, and orthogonal pH-reversible phenylboronic acid-diols were taken as "joints" to integrate them together. To verify the idea, a corona-core dual-polymer nanoassembly was prepared as the vehicle for lysosomotropic gene/drug co-delivery. Phenylboronic acid modified hyperbranched oligoethylenimine (OEI-PBA) was arranged to cluster around the hydrophobic core composed of hyperbranched polyglycerol, just by mixing two polymers in an appropriate ratio at neutral conditions. Compared with the parent OEI-PBA, this nanoassembly demonstrated better capture of plasmid DNA, highly enhanced activity for cellular transport and gene transfection (up to 100 fold), the ability to further load hydrophobic drugs, lysosome acidity-targeting pH-dependent release of both carried cargoes, and improved cell-biocompatibility. To evaluate its potential for combinational gene/drug therapy, in vitro experiments using the therapeutic p53 gene and antitumor doxorubicin as models were carried out. This intracellular co-delivery led to apparently synergetic anti-cancer effects in cultured cancer cells. This dynamic paradigm shows interesting features including easy manipulation, reversible conjugation, lysosome-targeting pH-responsiveness, high co-delivery efficiency, and functional expandability by further accommodating other building blocks. PMID:26221940

  11. Exploring hydrogen-bond capable backbone and ligating topologies: Co(II) coordination polymers derived from mixed ligand systems

    NASA Astrophysics Data System (ADS)

    Kumar, D. Krishna; Das, Amitava; Dastidar, Parthasarathi

    2006-08-01

    Three new coordination polymers namely {[Co(H 2O) 2(phthalate)(μL1)]·2.36H 2O} n1, {[Co(H 2O) 4(μL2)Co(H 2O) 2(phthalate) 2]·H 2O} n2 and {[Co(H 2O) 4(μL3)Co(H 2O) 2(phthalate) 2]·1.12H 2O} n3 [ L1= N-(4-pyridyl)isonicotinamide, L2= N-(3-pyridyl)isonicotinamide, L3= N-(4-pyridyl)nicotinamide] have been synthesized and characterized by single crystal X-ray diffraction, elemental analyses, IR, X-ray powder diffraction and thermogravimetric analyses. 1 and 2 crystallize in monoclinic P2 1/ n space group with cell dimensions a=8.2460(8) Å, b=13.5199(14) Å, c=19.609(2) Å, β=100.161(2)°, Z=4 and a=10.6653(8) Å, b=7.9952(6) Å, c=24.7444(17) Å, β=102.3790(10)°, Z=4, respectively. 3 crystallizes in monoclinic space group P2 1/ c with a=11.6556(8) Å, b=8.0359(6) Å, c=23.6344(17) Å, β=103.4040(10)° and Z=4. The metal centres in all the structures are hexacoordinated displaying slightly distorted octahedral geometry. Axial sites of the metal centres in all the cases are occupied by the nitrogen atoms of the bidentate ligands ( L1, L2 and L3) whereas the equatorial sites are occupied by the oxygen atoms coming from phthalate and water molecules. All the structures show 1D polymeric open framework capable of occluding hydrogen bonded guests such as water molecules.

  12. The influence of dispersed state on the structure and capability of the polymer electrolytes based on PVDF/PMMA

    NASA Astrophysics Data System (ADS)

    Yang, S. T.; Chen, H. J.; Jia, J. H.

    2002-12-01

    The polymer electrolyte which is firstly made by micro-wave inter-connect method and based on blended PVDF/PMMA and its conductivity is exceeding 10-3S · cm at room temperature. The result of polymer electrolytes that is dispersed by sub-micron SiO2 indicate that the mechanic intension is improved and the conductivity also improved. There is a new state with the test of the SEM and XRD and the non-crystal state of the polymer electrolytes have been improved after system adulteration which are favorable for the migration of Li+ and this is the expiation of the improvement of the conductivity of the polymer electrolytes.

  13. Control Capabilities of Low-Inductance-Antenna-Driven RF Plasmas for Low-Damage Processing of Polymers

    NASA Astrophysics Data System (ADS)

    Setsuhara, Yuichi; Takenaka, Kosuke; Cho, Ken; Ebe, Akinori; Shiratani, Masaharu; Sekine, Makoto; Hori, Masaru

    2008-10-01

    Low-damage processing of polymers is of key importance for fabrication of next-generation devices including electronics on polymers, which require development of plasma sources with reduced plasma potential in order to control interface between the polymer substrate and functional films without suffering degradations due to ion bombardment. Furthermore, applications to polymer-based displays and photovoltaic devices require ultra-large area processes at high throughput. To meet these requirements, we have developed plasma processing technologies with low-inductance antenna (LIA) modules to sustain inductively-coupled RF plasmas. Ion energy distributions showed considerably suppressed ion energy as low as 3.8 eV. The polymer surfaces after plasma exposure were analyzed via hard x-ray photoelectron spectroscopy (HXPES) at SPring8 (National SOR facility in Japan), which exhibited nano-surface modification of polymer surface without suffering degradation of molecular structures underneath. Furthermore, plasma-enhanced deposition of silicon films showed low-temperature (200 deg.C) formation of micro-crystalline silicon films due to sufficiently reduced damage during deposition.

  14. Mammalian cell cultures on micropatterned surfaces of weak-acid, polyelectrolyte hyperbranched thin films on gold.

    PubMed

    Amirpour, M L; Ghosh, P; Lackowski, W M; Crooks, R M; Pishko, M V

    2001-04-01

    A four-step soft lithographic process based on micro-contact printing of organic monolayers, hyperbranched polymer grafting, and subsequent polymer functionalization results in polymer/n-alkanethiol patterns that direct the growth and migration of mammalian cells. The functional units on these surfaces are three-dimensional cell "corrals" that have walls 52+/-2 nm in height and lateral dimensions on the order of 60 microm. The corrals have hydrophobic, methyl-terminated n-alkanethiol bottoms, which promote cell adhesion, and walls consisting of hydrophilic poly(acrylic acid)/poly(ethylene glycol) layered nanocomposites that inhibit cell growth. Cell viability studies indicate that cells remain viable on the patterned surfaces for up to 21 days, and fluorescence microscopy studies of stained cells demonstrate that cell growth and spreading does not occur outside of the corral boundaries. This simple, chemically flexible micropatterning method provides spatial control over growth of IC-21 murine peritoneal macrophages, human umbilical vein endothelial cells, and murine hepatocytes. PMID:11321309

  15. Peroxidase-like activity of gold nanoparticles stabilized by hyperbranched polyglycidol derivatives over a wide pH range

    NASA Astrophysics Data System (ADS)

    Drozd, Marcin; Pietrzak, Mariusz; Parzuchowski, Paweł; Mazurkiewicz-Pawlicka, Marta; Malinowska, Elżbieta

    2015-12-01

    The aim of this work was to carry out comparative studies on the peroxidase-like activity of gold nanoparticles (AuNPs) stabilized with low molecular weight hyperbranched polyglycidol (HBPG-OH) and its derivative modified with maleic acid residues (HBPG-COOH). The influence of the stabilizer to gold precursor ratio on the size and morphology of nanoparticles obtained was checked, and prepared nanoparticles were characterized by means of transmission electron microscopy and UV-Vis spectroscopy. The results indicated the divergent effect of increasing the concentration of stabilizers (HBPG-OH or HBPG-COOH) on the size of the nanostructures obtained. The gold nanoparticles obtained were characterized as having intrinsic peroxidase-like activity and the mechanism of catalysis in acidic and alkaline mediums was consistent with the standard Michaelis-Menten kinetics, revealing a strong affinity of AuNPs with 2, 2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 3, 3‧, 5, 5‧-tetramethylbenzidine (TMB), and significantly lower affinity towards phenol. By comparing the kinetic parameters, a negligible effect of polymeric ligand charge on activity against various types of substrates (anionic or cationic) was indicated. The superiority of steric stabilization via the application of tested low-weight hyperbranched polymers over typical stabilizers in preventing salt-induced aggregation and maintaining high catalytic activity in time was proved. The applied hyperbranched stabilizers provide a good tool for manufacturing gold-based nanozymes, which are highly stable and active over a wide pH range.

  16. Aggregation-Induced Emission in a Hyperbranched Poly(silylenevinylene) and Superamplification in Its Emission Quenching by Explosives.

    PubMed

    Lu, Ping; Lam, Jacky W Y; Liu, Jianzhao; Jim, Cathy K W; Yuan, Wangzhang; Xie, Ni; Zhong, Yongchun; Hu, Qin; Wong, Kam Sing; Cheuk, Kevin K L; Tang, Ben Zhong

    2010-05-12

    A silicon-containing hyperbranched polymer (hb-P1/2) with σ*-π* conjugation was prepared in a good yield and high molecular weight by rhodium-catalyzed alkyne polyhydrosilylation of 1,2-bis(4-ethynylphenyl)-1,2-diphenylethene (1) with tris(4-dimethylsilylphenyl)amine (2). The polymer was thermally stable, losing merely 5% of its weight when heated to ≈445 °C. Whereas hb-P1/2 was weakly luminescent when molecularly dissolved, it became highly emissive when supramolecularly aggregated, showing an aggregation-induced emission (AIE) phenomenon. A superamplification effect was observed when the AIE nanoaggregates were used as fluorescent chemosensor for explosive detection: the quenching efficiency was greatly increased in a nonlinear fashion with increasing quencher concentration. PMID:21590975

  17. Functionalization of graphene with hyperbranched polyglycerol for stable aqueous dispersion

    NASA Astrophysics Data System (ADS)

    Cai, Ning; Hou, Dajun; Shen, Liang; Luo, Xiaogang; Xue, Yanan; Yu, Faquan

    2015-07-01

    The application of graphene for some particular fields including biomedical engineering was hindered by its poor aqueous dispersivity and hydrophobic property. In this study, the strategy of the functionalization of graphene with hyperbranched polyglycerol (HPG) by a facile procedure was proposed. By the epoxy ring-opening hyperbranched polymerization of glycidol, graphene surface was grafted with HPG layer with rich hydroxyl groups. The content of polyglycerol on HPG functionalized graphene (HPG-G) was determined to be 55%. The results of fourier transform infrared (FTIR), X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS) and UV-Vis demonstrated that HPG was successfully grafted onto graphene sheets (GSs), and the aromatic and crystalline structure of graphene was maintained after HPG functionalization. The obtained HPG-G composites possess high hydrophilicity and can be dispersed well in water. Furthermore, no discernable precipitation was found in HPG-G aqueous solution even after three months of storage.

  18. Adsorption mechanism and valency of catechol-functionalized hyperbranched polyglycerols

    PubMed Central

    Krysiak, Stefanie; Wei, Qiang; Rischka, Klaus; Hartwig, Andreas; Haag, Rainer

    2015-01-01

    Summary Nature often serves as a model system for developing new adhesives. In aqueous environments, mussel-inspired adhesives are promising candidates. Understanding the mechanism of the extraordinarily strong adhesive bonds of the catechol group will likely aid in the development of adhesives. With this aim, we study the adhesion of catechol-based adhesives to metal oxides on the molecular level using atomic force microscopy (AFM). The comparison of single catechols (dopamine) with multiple catechols on hyperbranched polyglycerols (hPG) at various pH and dwell times allowed us to further increase our understanding. In particular, we were able to elucidate how to achieve strong bonds of different valency. It was concluded that hyperbranched polyglycerols with added catechol end groups are promising candidates for durable surface coatings. PMID:26150898

  19. Polymers.

    ERIC Educational Resources Information Center

    Tucker, David C.

    1986-01-01

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

  20. Optical nonlinearities in hyperbranched polyyne studied by two-photon excited fluorescence and third-harmonic generation spectroscopy

    NASA Astrophysics Data System (ADS)

    Castro-Beltran, R.; Ramos-Ortiz, G.; Jim, C. K. W.; Maldonado, J. L.; Häußler, M.; Peralta-Dominguez, D.; Meneses-Nava, M. A.; Barbosa-Garcia, O.; Tang, B. Z.

    2009-10-01

    The nonlinear optical properties of a hyperbranched polyyne ( hb-Polyyne) have been measured at infrared wavelengths by using femtosecond and nanosecond pulsed excitation. This hyperbranched polyyne exhibited strong and intrinsic (simultaneous) two-photon absorption and upconverted blue fluorescent emission under femtosecond excitation around 800 nm. The hb-Polyyne in chloroform solution is characterized by a large two-photon absorption cross section of 9068 GM (1 GM=10-50 cm4 s) and a fluorescence quantum yield of 0.57. On the other hand, by third-harmonic generation (THG) spectroscopy with nanosecond excitation, the measured third-order nonlinear susceptibility χ (3) for solid films of hb-Polyyne ranged from 2.4×10-11 to 6.1×10-11 esu in the spectral range of 1100-1600 nm, with results comparable to the values exhibited by the well-known conjugated polymer MEH:PPV, but with a much better transparency for visible wavelengths.

  1. Electrochemical immunosensor based on hyperbranched structure for carcinoembryonic antigen detection.

    PubMed

    Miao, Jingjing; Wang, Xiaobo; Lu, Liandi; Zhu, Peiyuan; Mao, Chun; Zhao, Haolin; Song, Youchao; Shen, Jian

    2014-08-15

    Sensitive determination of carcinoembryonic antigen (CEA) is very important in clinical research and diagnosis. Herein we report the design and synthesis of a new kind of immunosensor based on the benefits of hyperbranched structure. The hyperbranched polyester was grafted to the surface of indium tin oxides glass (ITO) electrode, and the grafting processes were characterized by attentuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). After CEA and horse radish peroxidase (HRP)-labeled antibody-conjugated AuNPs (HRP-Ab2-AuNPs) bioconjugates were immobilized on the surface of the hyperbranched structure-modified electrode, the optimized conditions of the above electrode were investigated. Moreover, the analytical performance of the proposed immunosensor showed a high sensitivity, a linear range from 0.01 to 80ng/mL with a low detection limit of 2.36pg/mL, and good selectivity for CEA. The designed immunoassay system holds great potential for ultrasensitive electrochemical biosensing of other analytes. PMID:24607616

  2. A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation

    PubMed Central

    Shen, Qi; Trabia, Sarah; Stalbaum, Tyler; Palmre, Viljar; Kim, Kwang; Oh, Il-Kwon

    2016-01-01

    Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors’ knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability. PMID:27080134

  3. A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation.

    PubMed

    Shen, Qi; Trabia, Sarah; Stalbaum, Tyler; Palmre, Viljar; Kim, Kwang; Oh, Il-Kwon

    2016-01-01

    Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors' knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability. PMID:27080134

  4. A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation

    NASA Astrophysics Data System (ADS)

    Shen, Qi; Trabia, Sarah; Stalbaum, Tyler; Palmre, Viljar; Kim, Kwang; Oh, Il-Kwon

    2016-04-01

    Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors’ knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability.

  5. Novel Low-Density Ablators Containing Hyperbranched Poly(azomethine)s

    NASA Technical Reports Server (NTRS)

    Tigelaar, Dean

    2011-01-01

    An ablative composite is low-density (0.25 to 0.40 g/cu cm), easy to fabricate, and superior to the current state-of-the-art ablator (phenolic impregnated carbon ablator, PICA) in terms of decomposition temperature, char yield, and mechanical strength. Initial ablative testing with a CO2 laser under high-heat-flux (1,100 W/sq cm) conditions showed these new ablators are over twice as effective as PICA in terms of weight loss, as well as transfer of heat through the specimen. The carbon fiber/poly(azomethine) composites have the same density as PICA, but are 8 to 11 times stronger to irreversible breaking by tensile compression. In addition, polyazomethine char yields by thermogravimetric analysis are 70 to 80 percent at 1,000 C. This char yield is 10 to 20 percent higher than phenolic resins, as well as one of the highest char yields known for any polymer. A high char yield holds the composite together better toward shearing forces on reentry, as well as reradiates high heat fluxes. This innovative composite is stronger than PICA, so multiple pieces can be sealed together without fracture. Researchers have also studied polyazomethines before as linear polymers. Due to poor solubility, these polymers precipitate from the polymerization solvent as a low-molecular-weight (2 to 4 repeat units) powder. The only way found to date to keep linear polyazomethines in solution is by adding solubilizing side groups. However, these groups sacrifice certain polymer properties. These hyperbranched polyazomethines are high molecular weight and fully aromatic.

  6. The use of azide-alkyne click chemistry in recent syntheses and applications of polytriazole-based nanostructured polymers

    NASA Astrophysics Data System (ADS)

    Shi, Yi; Cao, Xiaosong; Gao, Haifeng

    2016-02-01

    The rapid development of efficient organic click coupling reactions has significantly facilitated the construction of synthetic polymers with sophisticated branched nanostructures. This Feature Article summarizes the recent progress in the application of efficient copper-catalyzed and copper-free azide-alkyne cycloaddition (CuAAC and CuFAAC) reactions in the syntheses of dendrimers, hyperbranched polymers, star polymers, graft polymers, molecular brushes, and cyclic graft polymers. Literature reports on the interesting properties and functions of these polytriazole-based nanostructured polymers are also discussed to illustrate their potential applications as self-healing polymers, adhesives, polymer catalysts, opto-electronic polymer materials and polymer carriers for drug and imaging molecules.

  7. Enhanced electron extraction capability of polymer solar cells via modifying the cathode buffer layer with inorganic quantum dots.

    PubMed

    Li, Zhiqi; Li, Shujun; Zhang, Zhihui; Zhang, Xinyuan; Li, Jingfeng; Liu, Chunyu; Shen, Liang; Guo, Wenbin; Ruan, Shengping

    2016-04-20

    Enhanced performance of polymer solar cells (PSCs) based on the blend of poly[N-9''-hepta-decanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT):[6,6]-phenyl-C70-butyric acid methyl ester (PC71BM) is demonstrated by titanium dioxide (TiO2) interface modification via CuInS2/ZnS quantum dots (CZdots). Devices with a TiO2/CZdots composite buffer layer exhibit both a high short-circuit current density (Jsc) and fill factor (FF), leading to a power conversion efficiency (PCE) up to 7.01%. The charge transport recombination mechanisms are investigated by an impedance behavior model, which indicates that TiO2 interfacial modification results in not only increasing the electron extraction but also reducing impedance. This study provides an important and beneficial approach to develop high efficiency PSCs. PMID:27055908

  8. Enhanced Electron Extraction Capability of Polymer Solar Cells via Employing Electrostatically Self-Assembled Molecule on Cathode Interfacial Layer.

    PubMed

    Li, Zhiqi; Zhang, Xinyuan; Liu, Chunyu; Zhang, Zhihui; Li, Jinfeng; Shen, Liang; Guo, Wenbin; Ruan, Shengping

    2016-03-01

    In this paper, high-performance inverted polymer solar cells (PSCs) with a modified cathode buffer layer, titanium dioxide:polyethylenimine (TiO2:PEI), are demonstrated. The TiO2-O-PEI transport layer was fabricated by electrostatically self-assembled monolayers (ESAM) of PEI molecules. Protonated amine functional groups of PEI can combine protons (H(+)) hydrolyzing from its aqueous solution. Also, PEI could produce ESAM on the surface of hydroxylated TiO2 because of its cationic characteristics. The incorporation of the TiO2-O-PEI layer enhances the photocurrent and power conversion efficiency (PCE) due to the improved interfacial electron transport and extraction of the TiO2-O-PEI surface and the increased light absorption of the active layer. The enhanced PCE, low-cost materials, and solution process of TiO2-O-PEI buffer layers provide a promising method for highly efficient PSCs. PMID:26955888

  9. Bio-based hyperbranched thermosetting polyurethane/triethanolamine functionalized multi-walled carbon nanotube nanocomposites as shape memory materials.

    PubMed

    Kalita, Hemjyoti; Karak, Niranjan

    2014-07-01

    Here, bio-based shape memory polymers have generated immense interest in recent times. Here, Bio-based hyperbranched polyurethane/triethanolamine functionalized multi-walled carbon nanotube (TEA-f-MWCNT) nanocomposites were prepared by in-situ pre-polymerization technique. The Fourier transform infrared spectroscopy and the transmission electron microscopic studies showed the strong interfacial adhesion and the homogeneous distribution of TEA-f-MWCNT in the polyurethane matrix. The prepared epoxy cured thermosetting nanocomposites exhibited enhanced tensile strength (6.5-34.5 MPa), scratch hardness (3.0-7.5 kg) and thermal stability (241-288 degrees C). The nanocomposites showed excellent shape fixity and shape recovery. The shape recovery time decreases (24-10 s) with the increase of TEA-f-MWCNT content in the nanocomposites. Thus the studied nanocomposites have potential to be used as advanced shape memory materials. PMID:24758045

  10. Chain conformation and immunomodulatory activity of a hyperbranched polysaccharide from Cordyceps sinensis.

    PubMed

    Wu, Ding-Tao; Meng, Lan-Zhen; Wang, Lan-Ying; Lv, Guang-Ping; Cheong, Kit-Leong; Hu, De-Jun; Guan, Jia; Zhao, Jing; Li, Shao-Ping

    2014-09-22

    A polysaccharide, named as cordysinan, extracted from natural Cordyceps sinensis, was identified as a hyperbranched heteropolysaccharide from the results of FT-IR, GC-MS, and carbohydrate analysis by carbohydrate gel electrophoresis analysis, as well as the degree of branching of cordysinan was 43.3%. The solution properties of cordysinan were investigated by using size exclusion chromatography coupled with multi-angle laser light scattering and triple detector array, respectively. The molecular weights, the radius of gyration and the intrinsic viscosity of cordysinan were determined as 22.45±0.26 kDa and 22.37 kDa, 15.4±2.4 nm and 1.41 mL/g, respectively. By applying the polymer solution theory, the exponent (ν and α) values of g1/2=kMwv and [η]=kMwα were calculated as 0.28 and 0.42, respectively, which firstly revealed that cordysinan existed as a globular shape in 0.9% NaCl aqueous solution. Moreover, the results showed that cordysinan could obviously stimulate macrophages functions. PMID:24906773

  11. A Process and Environment Aware Sierra/SolidMechanics Cohesive Zone Modeling Capability for Polymer/Solid Interfaces

    SciTech Connect

    Reedy, E. D.; Chambers, Robert S.; Hughes, Lindsey Gloe; Kropka, Jamie Michael; Stavig, Mark E.; Stevens, Mark J.

    2015-09-01

    The performance and reliability of many mechanical and electrical components depend on the integrity of po lymer - to - solid interfaces . Such interfaces are found in adhesively bonded joints, encapsulated or underfilled electronic modules, protective coatings, and laminates. The work described herein was aimed at improving Sandia's finite element - based capability to predict interfacial crack growth by 1) using a high fidelity nonlinear viscoelastic material model for the adhesive in fracture simulations, and 2) developing and implementing a novel cohesive zone fracture model that generates a mode - mixity dependent toughness as a natural consequence of its formulation (i.e., generates the observed increase in interfacial toughness wi th increasing crack - tip interfacial shear). Furthermore, molecular dynamics simulations were used to study fundamental material/interfa cial physics so as to develop a fuller understanding of the connection between molecular structure and failure . Also reported are test results that quantify how joint strength and interfacial toughness vary with temperature.

  12. Nanostructured Amphiphilic Star-Hyperbranched Block Copolymers for Drug Delivery.

    PubMed

    Seleci, Muharrem; Seleci, Didem Ag; Ciftci, Mustafa; Demirkol, Dilek Odaci; Stahl, Frank; Timur, Suna; Scheper, Thomas; Yagci, Yusuf

    2015-04-21

    A robust drug delivery system based on nanosized amphiphilic star-hyperbranched block copolymer, namely, poly(methyl methacrylate-block-poly(hydroxylethyl methacrylate) (PMMA-b-PHEMA) is described. PMMA-b-PHEMA was prepared by sequential visible light induced self-condensing vinyl polymerization (SCVP) and conventional vinyl polymerization. All of the synthesis and characterization details of the conjugates are reported. To accomplish tumor cell targeting property, initially cell-targeting (arginylglycylaspactic acid; RGD) and penetrating peptides (Cys-TAT) were binding to each other via the well-known EDC/NHS chemistry. Then, the resulting peptide was further incorporated to the surface of the amphiphilic hyperbranched copolymer via a coupling reaction between the thiol (-SH) group of the peptide and the hydroxyl group of copolymer by using N-(p-maleinimidophenyl) isocyanate as a heterolinker. The drug release property and targeting effect of the anticancer drug (doxorobucin; DOX) loaded nanostructures to two different cell lines were evaluated in vitro. U87 and MCF-7 were chosen as integrin αvβ3 receptor positive and negative cells for the comparison of the targeting efficiency, respectively. The data showed that drug-loaded copolymers exhibited enhanced cell inhibition toward U87 cells in compared to MCF-7 cells because targeting increased the cytotoxicity of drug-loaded copolymers against integrin αvβ3 receptor expressing tumor cells. PMID:25816726

  13. Recent Advances in Simulation of Dendritic Polymers

    SciTech Connect

    Cagin, Tahir; Miklis, Paul J.; Wang, Guofeng; Zamanakos, Georgios; Martin, Ryan; Li, Hao; Mainz, Daniel T.; Nagarajan, V.; Goddard, William A.

    1999-05-11

    Dendrimers and hyperbranched polymers represent a revolution in methodology for directed synthesis of monodisperse polymers with enormous possibility of novel architectures. They demonstrate the ability to attain micelle-like structures with distinct internal and external character. Furthermore, the polyfunctional character of dendrimers allows varied response to environment and promise as selective sensors, carrier for drugs, encapsulation of toxic chemicals and metals. One of the key problems is the characterization of the structures. Theory and simulation can be essential to provide and predict structure and properties. We present some recent advances in theory, modeling and simulation of dendritic polymers.

  14. Liquid-Gel-Liquid Transition and Shear-Thickening in Mixed Suspensions of Silica Colloid and Hyperbranched Polyethyleneimine

    NASA Astrophysics Data System (ADS)

    Yuan, Guangcui; Zhang, Huan; Han, Charles C.

    2014-03-01

    The rheological property of mixed suspensions of silica colloid and hyperbranched polylethyleneimine was studied as functions of particle volume fraction, ratio of polymer to particle, and pH value. A mechanism of liquid-gel-liquid transition for this mixed system was proposed based on the amount and the conformation of polyelectrolyte bridges which were able to self-arrange with solution environments. The equilibrium adsorbed amount (Cp*) for a given volume fraction of particles is an important concentration ratio of polymer to particle denoting the transition of irreversible and reversible bridging. For mixed suspensions at equilibrium adsorbed state (Cp ~Cp *), the adsorption-desorption of polymer bridges on the particles can reversibly take place, and shear thickening is observed under a steady shear flow as a result of rapid extension of bridges when the relaxation time scale of extension is shorter than that of desorption. This work is supported by the National Basic Research Program of China (973 Program, 2012CB821503).

  15. Progesterone binding nano-carriers based on hydrophobically modified hyperbranched polyglycerols

    NASA Astrophysics Data System (ADS)

    Alizadeh Noghani, M.; Brooks, D. E.

    2016-02-01

    Progesterone (Pro) is a potent neurosteroid and promotes recovery from moderate Traumatic Brain Injury but its clinical application is severely impeded by its poor water solubility. Here we demonstrate that reversibly binding Pro within hydrophobically modified hyperbranched polyglycerol (HPG-Cn-MPEG) enhances its solubility, stability and bioavailability. Synthesis, characterization and Pro loading into HPG-Cn-MPEG is described. The release kinetics are correlated with structural properties and the results of Differential Scanning Calorimetry studies of a family of HPG-Cn-MPEGs of varying molecular weight and alkylation. While the maximum amount of Pro bound correlates well with the amount of alkyl carbon per molecule contributing to its hydrophobicity, the dominant first order rate constant for Pro release correlates strongly with the amount of structured or bound water in the dendritic domain of the polymer. The results provide evidence to justify more detailed studies of interactions with biological systems, both single cells and in animal models.Progesterone (Pro) is a potent neurosteroid and promotes recovery from moderate Traumatic Brain Injury but its clinical application is severely impeded by its poor water solubility. Here we demonstrate that reversibly binding Pro within hydrophobically modified hyperbranched polyglycerol (HPG-Cn-MPEG) enhances its solubility, stability and bioavailability. Synthesis, characterization and Pro loading into HPG-Cn-MPEG is described. The release kinetics are correlated with structural properties and the results of Differential Scanning Calorimetry studies of a family of HPG-Cn-MPEGs of varying molecular weight and alkylation. While the maximum amount of Pro bound correlates well with the amount of alkyl carbon per molecule contributing to its hydrophobicity, the dominant first order rate constant for Pro release correlates strongly with the amount of structured or bound water in the dendritic domain of the polymer. The

  16. Surface-initiated hyperbranched polyglycerol as an ultralow-fouling coating on glass, silicon, and porous silicon substrates.

    PubMed

    Moore, Eli; Delalat, Bahman; Vasani, Roshan; McPhee, Gordon; Thissen, Helmut; Voelcker, Nicolas H

    2014-09-10

    Anionic ring-opening polymerization of glycidol was initiated from activated glass, silicon, and porous silicon substrates to yield thin, ultralow-fouling hyperbranched polyglycerol (HPG) graft polymer coatings. Substrates were activated by deprotonation of surface-bound silanol functionalities. HPG polymerization was initiated upon the addition of freshly distilled glycidol to yield films in the nanometer thickness range. X-ray photoelectron spectroscopy, contact angle measurements, and ellipsometry were used to characterize the resulting coatings. The antifouling properties of HPG-coated surfaces were evaluated in terms of protein adsorption and the attachment of mammalian cells. The adsorption of bovine serum albumin and collagen type I was found to be reduced by as much as 97 and 91%, respectively, in comparison to untreated surfaces. Human glioblastoma and mouse fibroblast attachment was reduced by 99 and 98%, respectively. HPG-grafted substrates outperformed polyethylene glycol (PEG) grafted substrates of comparable thickness under the same incubation conditions. Our results demonstrate the effectiveness of antifouling HPG graft polymer coatings on a selected range of substrate materials and open the door for their use in biomedical applications. PMID:25137525

  17. Characterization of a Mixture of CO2 Adsorption Products in Hyperbranched Aminosilica Adsorbents by (13)C Solid-State NMR.

    PubMed

    Moore, Jeremy K; Sakwa-Novak, Miles A; Chaikittisilp, Watcharop; Mehta, Anil K; Conradi, Mark S; Jones, Christopher W; Hayes, Sophia E

    2015-11-17

    Hyperbranched amine polymers (HAS) grown from the mesoporous silica SBA-15 (hereafter "SBA-15-HAS") exhibit large capacities for CO2 adsorption. We have used static in situ and magic-angle spinning (MAS) ex situ (13)C nuclear magnetic resonance (NMR) to examine the adsorption of CO2 by SBA-15-HAS. (13)C NMR distinguishes the signal of gas-phase (13)CO2 from that of the chemisorbed species. HAS polymers possess primary, secondary, and tertiary amines, leading to multiple chemisorption reaction outcomes, including carbamate (RnNCOO(-)), carbamic acid (RnNCOOH), and bicarbonate (HCO3(-)) moieties. Carbamates and bicarbonate fall within a small (13)C chemical shift range (162-166 ppm), and a mixture was observed including carbamic acid and carbamate, the former disappearing upon evacuation of the sample. By examining the (13)C-(14)N dipolar coupling through low-field (B0 = 3 T) (13)C{(1)H} cross-polarization MAS NMR, carbamate is confirmed through splitting of the (13)C resonance. A third species that is either bicarbonate or a second carbamate is evident from bimodal T2 decay times of the ∼163 ppm peak, indicating the presence of two species comprising that single resonance. The mixture of products suggests that (1) the presence of amines and water leads to bicarbonate being present and/or (2) the multiple types of amine sites in HAS permit formation of chemically distinct carbamates. PMID:26477882

  18. Conjugated hyperbranched poly(aryleneethynylene)s: synthesis, photophysical properties, superquenching by explosive, photopatternability, and tunable high refractive indices.

    PubMed

    Yuan, Wang Zhang; Hu, Rongrong; Lam, Jacky W Y; Xie, Ni; Jim, Cathy K W; Tang, Ben Zhong

    2012-03-01

    Triphenylamine (TPA)-based conjugated hyperbranched poly(aryleneethynylene)s (PAEs), hb-P1/2, hb-P1/3, and hb-P1/4, were synthesized with high molecular weights and good solubilities through Sonogashira coupling reactions. These PAEs exhibited outstanding thermal stabilities and different emission behaviors. Tetraphenylethene (TPE)-containing hb-P1/2 fluoresced faintly in THF, although its light emission was enhanced by aggregate formation in aqueous media or in thin films, thereby exhibiting an aggregation-induced emission-enhancement (AIEE) effect. Whereas 1,1,2,3,4,5-hexaphenylsilole (HPS)-bearing hb-P1/3 showed no significant change in emission intensity with increasing water content in aqueous media, hb-P1/4, which consisted of TPA-fluorenone donor-acceptor groups, presented almost identical absorptions, but both positive and negative solvatochromic emissions in various solvents. A superquenching effect was observed in the picric-acid-detection process by using nanosuspensions of hb-P1/2. All of the polymers possessed good film formability. UV irradiation of the thin films induced simultaneous photobleaching and cross-linking, thus making them applicable in the fabrication of 2D and 3D patterns. Furthermore, the polymer films also showed high refractive indices, which were tunable upon exposure to UV light. PMID:22298493

  19. Anti-fouling behavior of hyperbranched polyglycerol-grafted poly(ether sulfone) hollow fiber membranes for osmotic power generation.

    PubMed

    Li, Xue; Cai, Tao; Chung, Tai-Shung

    2014-08-19

    To sustain high performance of osmotic power generation by pressure-retarded osmosis (PRO) processes, fouling on PRO membranes must be mitigated. This is especially true for the porous support of PRO membranes because its porous structure is very prone to fouling by feeding river water. For the first time, we have successfully designed antifouling PRO thin-film composite (TFC) membranes by synthesizing a dendritic hydrophilic polymer with well-controlled grafting sites, hyperbranched polyglycerol (HPG), and then grafting it on poly(ether sulfone) (PES) hollow fiber membrane supports. Compared to the pristine PES membranes, polydopamine modified membranes, and conventional poly(ethylene glycol) (PEG)-grafted membranes, the HPG grafted membranes show much superior fouling resistance against bovine serum albumin (BSA) adsorption, E. coli adhesion, and S. aureus attachment. In high-pressure PRO tests, the PES TFC membranes are badly fouled by model protein foulants, causing a water flux decline of 31%. In comparison, the PES TFC membrane grafted by HPG not only has an inherently higher water flux and a higher power density but also exhibits better flux recovery up to 94% after cleaning and hydraulic pressure impulsion. Clearly, by grafting the properly designed dendritic polymers to the membrane support, one may substantially sustain PRO hollow fiber membranes for power generation. PMID:25019605

  20. Development and in vitro characterization of paclitaxel and docetaxel loaded into hydrophobically derivatized hyperbranched polyglycerols.

    PubMed

    Mugabe, C; Liggins, R T; Guan, D; Manisali, I; Chafeeva, I; Brooks, D E; Heller, M; Jackson, J K; Burt, H M

    2011-02-14

    In this study we report the development and in vitro characterization of paclitaxel (PTX) and docetaxel (DTX) loaded into hydrophobically derivatized hyperbranched polyglycerols (HPGs). Several HPGs derivatized with hydrophobic groups (C(8/10) alkyl chains) (HPG-C(8/10)-OH) and/or methoxy polyethylene glycol (MePEG) chains (HPG-C(8/10)-MePEG) were synthesized. PTX or DTX were loaded into these polymers by a solvent evaporation method and the resulting nanoparticle formulations were characterized in terms of size, drug loading, stability, release profiles, cytotoxicity, and cellular uptake. PTX and DTX were found to be chemically unstable in unpurified HPGs and large fractions (∼80%) of the drugs were degraded during the preparation of the formulations. However, both PTX and DTX were found to be chemically stable in purified HPGs. HPGs possessed hydrodynamic radii of less than 10nm and incorporation of PTX or DTX did not affect their size. The release profiles for both PTX and DTX from HPG-C(8/10)-MePEG nanoparticles were characterized by a continuous controlled release with little or no burst phase of release. In vitro cytotoxicity evaluations of PTX and DTX formulations demonstrated a concentration-dependent inhibition of proliferation in KU7 cell line. Cellular uptake studies of rhodamine-labeled HPG (HPG-C(8/10)-MePEG(13)-TMRCA) showed that these nanoparticles were rapidly taken up into cells, and reside in the cytoplasm without entering the nuclear compartment and were highly biocompatible with the KU7 cells. PMID:21093563

  1. Cross-Linked Hyperbranched Polyglycerols as Hosts for Selective Binding of Guest Molecules

    PubMed Central

    Burakowska, Ewelina; Quinn, Jordan R.; Zimmerman, Steven C.; Haag, Rainer

    2009-01-01

    The ring-closing metathesis reaction of dendrimers containing allyl ether end groups is known to rigidify them significantly. Herein we report that polyallylated hyperbranched polyglycerol (HPG) 1 complexes the sodium salt of rose Bengal in chloroform solution but releases it readily to water. In contrast, extensively cross-linking 1 with Grubbs catalyst provides 2 which similarly complexes rose Bengal, but does not release it despite 12 h of shaking with water. Both 1 and 2 also complex thymol blue and exhibit the same differential complex stability when extracted with water. Neither 1 nor 2 complex Congo red sodium salt and more weakly solubilize the cesium salt of rose Bengal and thymol blue. Larger loop size cross-linked analogs HPG 5 and 6 also bind rose Bengal (RB) and thymol blue and are able to bind Congo red, but both release the dye more readily when extracted with water. In addition, a bathochromic shift is observed in the UV spectra for complex 6·RB, suggesting a changed microenvironment for the dye due to a tighter binding of the counter anion. Dihydroxylation of the alkene groups in 1, 2, 5, and 6 produced HPGs 3, 4, 7, and 8, respectively. HPGs 3 and 4 are both water-soluble, but 7 and 8 were not and could not be studied further. In water, HPG 4 solubilized less than one nonpolar guest (Nimodipine, pyrene, or Nile red) per polymer at least in part because it forms very large aggregates. Dynamic light scattering (DLS) and size exclusion chromatography (SEC) indicate aggregates with diameters of ca. 100 nm in pure water. The aggregates dissociated in high salt concentrations suggesting applications in stimuli responsive materials. PMID:19722631

  2. Lipase-catalyzed synthesis of hyperbranched poly-L-lactide in an ionic liquid.

    PubMed

    Mena, María; López-Luna, Alberto; Shirai, Keiko; Tecante, Alberto; Gimeno, Miquel; Bárzana, Eduardo

    2013-03-01

    Hyperbranched poly-L-lactides have been synthesized by eROP in [C4MIM][PF6] media. The bis(hydroxymethyl)butyric acid molecule was used as the AB2 core co-monomer and immobilized lipase B from Candida antarctica as biocatalyst. The degree of branching could be controlled by the reaction conditions, with the maximum achieved being 0.21. The successful achievement of the hyperbranched structure is attributed to the high solvent power of substrates and products in the ionic liquid besides sustained lipase activity. PMID:22869004

  3. Enhanced dispersion of carbon nanotubes in hyperbranched polyurethane and properties of nanocomposites

    NASA Astrophysics Data System (ADS)

    Rana, Sravendra; Karak, Niranjan; Cho, Jae Whan; Kim, Young Ho

    2008-12-01

    Hyperbranched polyurethane (HBPU) nanocomposites with multi-walled carbon nanotubes (MWNTs) were prepared by in situ polymerization on the basis of poly(ɛ-caprolactone)diol as the soft segment, 4,4'-methylene bis(phenylisocyanate) as the hard segment, and castor oil as the multifunctional group for the hyperbranched structure. A dominant improvement in the dispersion of MWNTs in the HBPU matrix was found, and good solubility of HBPU-MWNT nanocomposites in organic solvents was shown. Due to the well-dispersed MWNTs, the nanocomposites resulted in achieving excellent shape memory properties as well as enhanced mechanical properties compared to pure HBPU.

  4. One-pot synthesis of doxorubicin-loaded multiresponsive nanogels based on hyperbranched polyglycerol.

    PubMed

    Sousa-Herves, Ana; Wedepohl, Stefanie; Calderón, Marcelo

    2015-03-28

    Doxorubicin-loaded nanogels with multiresponsive properties are prepared using hyperbranched polyglycerol as a biocompatible scaffold. The nanogels are synthesized in a single step combining free-radical polymerization and a mild nanoprecipitation technique. The nanogels respond to different biological stimuli such as low pH and reductive environments, resulting in a more efficient cell proliferation inhibition in A549 cells. PMID:25757793

  5. Characterization of hyperbranched glycopolymers produced in vitro using enzymes.

    PubMed

    Rolland-Sabaté, Agnès; Guilois, Sophie; Grimaud, Florent; Lancelon-Pin, Christine; Roussel, Xavier; Laguerre, Sandrine; Viksø-Nielsen, Anders; Putaux, Jean-Luc; D'Hulst, Christophe; Potocki-Véronèse, Gabrielle; Buléon, Alain

    2014-02-01

    Asymmetrical flow field flow fractionation (AF4) has proven to be a very powerful and quantitative method for the determination of the macromolecular structure of high molar mass branched biopolymers, when coupled with multi-angle laser light scattering (MALLS). This work describes a detailed investigation of the macromolecular structure of native glycogens and hyperbranched α-glucans (HBPs), with average molar mass ranging from 2 × 10(6) to 4.3 × 10(7) g mol(-1), which are not well fractionated by means of classical size-exclusion chromatography. HBPs were enzymatically produced from sucrose by the tandem action of an amylosucrase and a branching enzyme mimicking in vitro the elongation and branching steps involved in glycogen biosynthesis. Size and molar mass distributions were studied by AF4, coupled with online quasi-elastic light scattering (QELS) and transmission electron microscopy. AF4-MALLS-QELS has shown a remarkable agreement between hydrodynamic radii obtained by online QELS and by AF4 theory in normal mode with constant cross flow. Molar mass, size, and dispersity were shown to significantly increase with initial sucrose concentration, and to decrease when the branching enzyme activity increases. Several populations with different size range were observed: the amount of small size molecules decreasing with increasing sucrose concentration. The spherical and dense global conformation thus highlighted was partly similar to native glycogens. A more detailed study of HBPs synthesized from low and high initial sucrose concentrations was performed using complementary enzymatic hydrolysis of external chains and chromatography. It emphasized a more homogeneous branching pattern than native glycogens with a denser core and shorter external chains. PMID:24220756

  6. Terminal index: a new way for precise description of topologic structure of highly branched polymers derived from A2 + B3 stepwise polymerization.

    PubMed

    Chen, Heng; Kong, Jie

    2014-03-27

    Terminal index (TI) was presented as a new characteristic parameter for quantitative description of branched and cyclic topology of highly branched soluble polymers derived from A2 + B3 stepwise polymerization. TI is defined as the ratio of terminal units of an A2 + B3 type highly branched polymer to those in its perfect hyperbranched counterpart. TI is concisely represented as T/(D + L), which can be conveniently calculated from a quantitative NMR spectrum. The model of soluble A2 + B3 type polymers is suggested as an intermediate between multicyclic polymers and perfect hyperbranched polymers. The TI ranges between 0 and 1 where a higher TI indicates a perfect hyperbranched topology while a low TI indicates a multicyclic structure. The analysis of soluble A2 + B3 type polyesters and polycarbosilanes as model polymers demonstrates that TI as a more precise parameter, along with degree of branching, can be generally applied to understand the fine topology of highly branched polymers derived from A2 + B3 polymerization. PMID:24579792

  7. Secondary and primary relaxations in hyperbranched polyglycerol: a comparative study in the frequency and time domains.

    PubMed

    Garcia-Bernabé, Abel; Dominguez-Espinosa, Gustavo; Diaz-Calleja, Ricardo; Riande, Evaristo; Haag, Rainer

    2007-09-28

    The non-Debye relaxation behavior of hyperbranched polyglycerol was investigated by broadband dielectric spectroscopy. A thorough study of the relaxations was carried out paying special attention to truncation effects on deconvolutions of overlapping processes. Hyperbranched polyglycerol exhibits two relaxations in the glassy state named in increasing order of frequency beta and gamma processes. The study of the evolution of these two fast processes with temperature in the time retardation spectra shows that the beta absorption is swallowed by the alpha in the glass-liquid transition, the gamma absorption being the only relaxation that remains operative in the liquid state. In heating, a temperature is reached at which the alpha absorption vanishes appearing the alphagamma relaxation. Two characteristics of alpha absorptions, decrease of the dielectric strength with increasing temperature and rather high activation energy, are displayed by the alphagamma process. Williams' ansatz seems to hold for these topologically complex macromolecules. PMID:17902934

  8. A hyperbranched polyethylenimine functionalized stationary phase for hydrophilic interaction liquid chromatography.

    PubMed

    Peng, Yahui; Hou, Yanjie; Zhang, Feifang; Shen, Guobin; Yang, Bingcheng

    2016-05-01

    A hyperbranched stationary phase for hydrophilic interaction liquid chromatography (HILIC) has been prepared by grafting polyethylenimine (PEI) onto silica gel (termed as PEI-Sil). Rich primary, secondary, and tertiary amino groups associated with PEI render its good hydrophility. More importantly, the hyperbranched structure of PEI molecule is greatly helpful in improving interaction with polar analytes. For several kinds of model polar compounds, including organic acids, nucleosides, nucleic acid bases, amino acids, cephalosporins, and non-reducing sugars, PEI-Sil demonstrated excellent separation performance in terms of running stability, reproducibility, and separation efficiency (e.g., plate count ~74,000/m). In addition, PEI-Sil also exhibited much better separation selectivity toward inorganic anions when operated in the mode of ion chromatography relative to a commercial amino propyl-bonded column. PMID:26970747

  9. Secondary and primary relaxations in hyperbranched polyglycerol: A comparative study in the frequency and time domains

    NASA Astrophysics Data System (ADS)

    Garcia-Bernabé, Abel; Dominguez-Espinosa, Gustavo; Diaz-Calleja, Ricardo; Riande, Evaristo; Haag, Rainer

    2007-09-01

    The non-Debye relaxation behavior of hyperbranched polyglycerol was investigated by broadband dielectric spectroscopy. A thorough study of the relaxations was carried out paying special attention to truncation effects on deconvolutions of overlapping processes. Hyperbranched polyglycerol exhibits two relaxations in the glassy state named in increasing order of frequency β and γ processes. The study of the evolution of these two fast processes with temperature in the time retardation spectra shows that the β absorption is swallowed by the α in the glass-liquid transition, the γ absorption being the only relaxation that remains operative in the liquid state. In heating, a temperature is reached at which the α absorption vanishes appearing the αγ relaxation. Two characteristics of α absorptions, decrease of the dielectric strength with increasing temperature and rather high activation energy, are displayed by the αγ process. Williams' ansatz seems to hold for these topologically complex macromolecules.

  10. Rheology of Hyperbranched Poly(triglyceride)-Based Thermoplastic Elastomers via RAFT polymerization

    NASA Astrophysics Data System (ADS)

    Yan, Mengguo; Cochran, Eric

    2014-03-01

    In this contribution we discuss how melt- and solid-state properties are influenced by the degree of branching and molecular weight in a family of hyperbranched thermoplastics derived from soybean oil. Acrylated epoxidized triglycerides from soybean oils have been polymerized to hyperbranched thermoplastic elastomers using reversible addition-fragmentation chain transfer (RAFT) polymerization. With the proper choice of chain transfer agent, both homopolymer and block copolymer can be synthesized. By changing the number of acrylic groups per triglycerides, the chain architectures can range from nearly linear to highly branched. We show how the fundamental viscoelastic properties (e.g. entanglement molecular weight, plateau modulus, etc.) are influenced by chain architecture and molecular weight.

  11. Induced Mesophase in Mixtures of Photopolymerizable Hyperbranched Polyester and Liquid Crystal Mesogen

    NASA Astrophysics Data System (ADS)

    Kim, Namil; Kyu, Thein; Nosaka, Mami; Kudo, Hiroto; Nishikubo, Tadatomi

    2008-03-01

    Phase behavior of a mixture of eutectic liquid crystals (E7) and hyperbranched polyester (HBPEAc-COOH) has been investigated using polarized optical microscopy and differential scanning calorimetry. The observed phase diagram is an upper azeotrope, exhibiting the coexistence of nematic + isotropic phase in the vicinity of 90˜110^oC above the clearing temperature of neat E7 (60^oC). With decreasing temperature a focal-conic fan shaped texture develops in the composition range of 70˜90 wt% of E7, suggestive of induced smectic Sm-A phase in the mixture containing no known smectic phase in their neat forms. Wide angle x-ray diffraction (WAXD) technique revealed the existence of higher order mesophase(s). The phenomenon of induced mesophase in the hyperbranched polyester/E7 system will be discussed.

  12. Facile synthesis of dendritic gold nanostructures with hyperbranched architectures and their electrocatalytic activity toward ethanol oxidation.

    PubMed

    Huang, Jianshe; Han, Xinyi; Wang, Dawei; Liu, Dong; You, Tianyan

    2013-09-25

    Gold dendritic nanostructures with hyperbranched architectures were synthesized by the galvanic replacement reaction between nickel wire and HAuCl4 in aqueous solution. The study revealed that the morphology of the obtained nanostructures strongly depended on experimental parameters such as the HAuCl4 solution concentration, reaction temperature, and time, as well as stirring or not. According to the investigation of the growth process, it was proposed that gold nanoparticles with rough surfaces were first deposited on the nickel substrate and that subsequent growth preferentially occurred on the preformed gold nanoparticles, finally leading to the formation of hyperbranched gold dendrites via a self-organization process under nonequilibrium conditions. The electrochemical experiment results demonstrated that the as-obtained gold dendrites exhibited high catalytic activity toward ethanol electrooxidation in alkaline solution, indicating that this nanomaterial may be a potential catalyst for direct ethanol fuel cells. PMID:23972030

  13. Preparation and catalytic ability to reduce hydrogen peroxide of Ag nanoparticles highly dispersed via hyperbranched copolymer

    NASA Astrophysics Data System (ADS)

    Yao, Lu; Yang, Weiying; Yang, Jie; He, Linghao; Sun, Jing; Song, Rui; Ma, Zhi; Huang, Wei

    2011-03-01

    Highly dispersed Ag nanoparticles, stabilized by hyperbranched copolymers (HPCs), were prepared by chemical reduction in toluene. These Ag NPs were used further for the fabrication of a hydrogen peroxide (H2O2) sensor, by which a good catalytic ability for the reduction of H2O2 was found.Highly dispersed Ag nanoparticles, stabilized by hyperbranched copolymers (HPCs), were prepared by chemical reduction in toluene. These Ag NPs were used further for the fabrication of a hydrogen peroxide (H2O2) sensor, by which a good catalytic ability for the reduction of H2O2 was found. Electronic supplementary information (ESI) available: Structure and structure parameters of the HPCs, and UV-vis and XPS spectra of the NPs . See DOI: 10.1039/c0nr00567c

  14. Hyperbranched Hybridization Chain Reaction for Triggered Signal Amplification and Concatenated Logic Circuits.

    PubMed

    Bi, Sai; Chen, Min; Jia, Xiaoqiang; Dong, Ying; Wang, Zonghua

    2015-07-01

    A hyper-branched hybridization chain reaction (HB-HCR) is presented herein, which consists of only six species that can metastably coexist until the introduction of an initiator DNA to trigger a cascade of hybridization events, leading to the self-sustained assembly of hyper-branched and nicked double-stranded DNA structures. The system can readily achieve ultrasensitive detection of target DNA. Moreover, the HB-HCR principle is successfully applied to construct three-input concatenated logic circuits with excellent specificity and extended to design a security-mimicking keypad lock system. Significantly, the HB-HCR-based keypad lock can alarm immediately if the "password" is incorrect. Overall, the proposed HB-HCR with high amplification efficiency is simple, homogeneous, fast, robust, and low-cost, and holds great promise in the development of biosensing, in the programmable assembly of DNA architectures, and in molecular logic operations. PMID:26012841

  15. Synthesis of Cu-Ag@Ag particles using hyperbranched polyester as template

    NASA Astrophysics Data System (ADS)

    Han, Wen-Song

    2015-07-01

    In this manuscript, the third-generation hyperbranched polyester was synthesized with 2, 2-dimethylol propionic acid as AB2 monomer and pentaerythrite as core molecule by using step by step polymerization process at first. Then, the Cu-Ag particles were prepared by co-reduction of silver nitrate and copper nitrate with ascorbic acid in the aqueous solution using hyperbranched polyester as template. Finally, the Cu-Ag@Ag particles were prepared by coating silver on the surface of Cu-Ag particles by reduction of silver nitrate. The synthesized hyperbranched polyester and Cu-Ag@Ag particles were characterized by Fourier transform infrared (FT-IR) spectroscopy, UV-vis spectra, x-ray diffraction, Laser light scattering, thermogravimetric analysis (TGA) and SEM. UV-vis spectra results showed that the Cu-Ag@Ag particles had a strong absorption band at around 420 nm. Laser light scattering and SEM studies confirmed that the most frequent particle sizes of Cu-Ag@Ag particles were 1.2 um. TGA results indicated that the Cu-Ag@Ag particles had good thermal stability. [Figure not available: see fulltext.

  16. Magnetoceramics from the bulk pyrolysis of polysilazane cross-linked by polyferrocenylcarbosilanes with hyperbranched topology.

    PubMed

    Kong, Jie; Kong, Minmin; Zhang, Xiaofei; Chen, Lixin; An, Linan

    2013-10-23

    In this contribution, we report a novel strategy for the synthesis of nanocrystal-containing magnetoceramics with an ultralow hysteresis loss by the pyrolysis of commercial polysilazane cross-linked with a functional metallopolymer possessing hyperbranched topology. The usage of hyperbranched polyferrocenylcarbosilane offers either enhanced ceramic yield or magnetic functionality of pyrolyzed ceramics. The ceramic yield was enhanced accompanied by a decreased evolution of hydrocarbons and NH3 because of the cross-linking of precursors and the hyperbranched cross-linker. The nucleation of Fe5Si3 from the reaction of iron atoms with Si-C-N amorphous phase promoted the formation of α-Si3N4 and SiC crystals. After annealing at 1300 °C, stable Fe3Si crystals were generated from the transformation of the metastable Fe5Si3 phase. The nanocrystal-containing ceramics showed good ferromagnetism with an ultralow (close to 0) hysteresis loss. This method is convenient for the generation of tunable functional ceramics using a commercial polymeric precursor cross-linked by a metallopolymer with a designed topology. PMID:24060298

  17. Noradrenaline-functionalized hyperbranched fluoropolymer-poly(ethylene glycol) cross-linked networks as dual-mode, anti-biofouling coatings.

    PubMed

    Imbesi, Philip M; Gohad, Neeraj V; Eller, Michael J; Orihuela, Beatriz; Rittschof, Dan; Schweikert, Emile A; Mount, Andrew S; Wooley, Karen L

    2012-02-28

    The strategy of decorating antibiofouling hyperbranched fluoropolymer-poly(ethylene glycol) (HBFP-PEG) networks with a settlement sensory deterrent, noradrenaline (NA), and the results of biofouling assays are presented. This example of a dual-mode surface, which combines both passive and active modes of antibiofouling, works in synergy to improve the overall antibiofouling efficiency against barnacle cyprids. The HBFP-PEG polymer surface, prior to modification with NA, was analyzed by atomic force microscopy, and a significant distribution of topographical features was observed, with a nanoscopic roughness measurement of 110 ± 8 nm. NA attachment to the surface was probed by secondary ion mass spectrometry to quantify the extent of polymer chain-end substitution with NA, where a 3- to 4-fold increase in intensity for a fragment ion associated with NA was observed and 39% of the available sites for attachment were substituted. Cytoskeletal assays confirmed the activity of tethered NA on adhering oyster hemocytes. Settlement assays showed deterrence toward barnacle cyprid settlement, while not compromising the passive biofouling resistance of the surface. This robust strategy demonstrates a methodology for the incorporation of actively antibiofouling moieties onto a passively antibiofouling network. PMID:22276525

  18. GMI Capabilities

    NASA Technical Reports Server (NTRS)

    Strode, Sarah; Rodriguez, Jose; Steenrod, Steve; Liu, Junhua; Strahan, Susan; Nielsen, Eric

    2015-01-01

    We describe the capabilities of the Global Modeling Initiative (GMI) chemical transport model (CTM) with a special focus on capabilities related to the Atmospheric Tomography Mission (ATom). Several science results based on GMI hindcast simulations and preliminary results from the ATom simulations are highlighted. We also discuss the relationship between GMI and GEOS-5.

  19. Composite Electrolytes for Lithium Batteries: Ionic Liquids in APTES Crosslinked Polymers

    NASA Technical Reports Server (NTRS)

    Tigelaar, Dean M.; Meador, Mary Ann B.; Bennett, William R.

    2007-01-01

    Solvent free polymer electrolytes were made consisting of Li(+) and pyrrolidinium salts of trifluoromethanesulfonimide added to a series of hyperbranched poly(ethylene oxide)s (PEO). The polymers were connected by triazine linkages and crosslinked by a sol-gel process to provide mechanical strength. The connecting PEO groups were varied to help understand the effects of polymer structure on electrolyte conductivity in the presence of ionic liquids. Polymers were also made that contain poly(dimethylsiloxane) groups, which provide increased flexibility without interacting with lithium ions. When large amounts of ionic liquid are added, there is little dependence of conductivity on the polymer structure. However, when smaller amounts of ionic liquid are added, the inherent conductivity of the polymer becomes a factor. These electrolytes are more conductive than those made with high molecular weight PEO imbibed with ionic liquids at ambient temperatures, due to the amorphous nature of the polymer.

  20. Adsorption properties of hyperbranched aliphatic polyester grafted attapulgite towards heavy metal ions.

    PubMed

    Liu, Peng; Wang, Tingmei

    2007-10-01

    The AB(2) type monomer, 2,2-bis (hydroxymethyl) propionic acid (bis-MPA), was successfully grafted from the surfaces of the amino groups modified attapulgite nano-fibrillar clay (A-ATP) via a melt polycondensation method with p-toluenesulfonic acid (p-TSA) as catalyst. The competitive adsorption properties of the hyperbranched aliphatic polyester grafted attapulgite (HAPE-ATP) towards the heavy metal ions (Cu(II), Hg(II), Zn(II), and Cd(II)) were investigated preliminarily. PMID:17467898

  1. An efficient nonviral gene-delivery vector based on hyperbranched cationic glycogen derivatives

    PubMed Central

    Liang, Xuan; Ren, Xianyue; Liu, Zhenzhen; Liu, Yingliang; Wang, Jue; Wang, Jingnan; Zhang, Li-Ming; Deng, David YB; Quan, Daping; Yang, Liqun

    2014-01-01

    Background The purpose of this study was to synthesize and evaluate hyperbranched cationic glycogen derivatives as an efficient nonviral gene-delivery vector. Methods A series of hyperbranched cationic glycogen derivatives conjugated with 3-(dimethylamino)-1-propylamine (DMAPA-Glyp) and 1-(2-aminoethyl) piperazine (AEPZ-Glyp) residues were synthesized and characterized by Fourier-transform infrared and hydrogen-1 nuclear magnetic resonance spectroscopy. Their buffer capacity was assessed by acid–base titration in aqueous NaCl solution. Plasmid deoxyribonucleic acid (pDNA) condensation ability and protection against DNase I degradation of the glycogen derivatives were assessed using agarose gel electrophoresis. The zeta potentials and particle sizes of the glycogen derivative/pDNA complexes were measured, and the images of the complexes were observed using atomic force microscopy. Blood compatibility and cytotoxicity were evaluated by hemolysis assay and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay, respectively. pDNA transfection efficiency mediated by the cationic glycogen derivatives was evaluated by flow cytometry and fluorescence microscopy in the 293T (human embryonic kidney) and the CNE2 (human nasopharyngeal carcinoma) cell lines. In vivo delivery of pDNA in model animals (Sprague Dawley rats) was evaluated to identify the safety and transfection efficiency. Results The hyperbranched cationic glycogen derivatives conjugated with DMAPA and AEPZ residues were synthesized. They exhibited better blood compatibility and lower cytotoxicity when compared to branched polyethyleneimine (bPEI). They were able to bind and condense pDNA to form the complexes of 100–250 nm in size. The transfection efficiency of the DMAPA-Glyp/pDNA complexes was higher than those of the AEPZ-Glyp/pDNA complexes in both the 293T and CNE2 cells, and almost equal to those of bPEI. Furthermore, pDNA could be more safely delivered to the blood vessels in brain

  2. Studies on influence of polymer modifiers for fluorescent nanocrystals' cytotoxicity.

    PubMed

    Grabowska-Jadach, Ilona; Drozd, Marcin; Biegala, Joanna; Pietrzak, Mariusz; Mazurkiewicz-Pawlicka, Marta; Parzuchowski, Paweł G; Brzózka, Zbigniew

    2016-08-01

    The presented studies aimed at investigation of the effect of CdSeS/ZnS quantum dots (QDs) stabilized with hyperbranched polyglycidol and its carboxylated derivative on adenocarcinomic human alveolar basal epithelial cells (A549). The first stage of studies concerned the modification of quantum dots with both types of the tested polymers with the use of pyridine as an intermediate agent. Subsequently, cytotoxic effect of the prepared nanoparticles was examined after various incubation time using MTT test (cell metabolic activity assay). Our studies revealed that CdSeS/ZnS with a diameter of 6nm, which were stabilized with hyperbranched polymers do not penetrate into cells, even after prolonged incubation time. Moreover, the cytotoxic effect of the tested QDs was observed over a range of tested concentrations (5-90μM of Cd(2+)). It was confirmed that tested nanoparticles had significant influence on cell culture viability. The examined cytotoxic effect of the tested quantum dots was dependent on the type of polymer applied and the experiments indicated, that the one bearing carboxylic moieties is more toxic to A549 cells. PMID:26997161

  3. Spiropyran-based hyperbranched star copolymer: synthesis, phototropy, FRET, and bioapplication.

    PubMed

    Wang, Ying; Hong, Chun-Yan; Pan, Cai-Yuan

    2012-08-13

    Photo- and pH-responsive amphiphilic hyperbranched star copolymers, poly(6-O-methacryloyl-1,2;3,4-di-O-isopropylidene-d-galactopyranose)[poly(2-(N,N-dimethylaminoethyl) methacrylate)-co-poly(1'-(2-methacryloxyethyl)-3',3'-dimethyl-6-nitro-spiro(2H-1-benzo-pyran-2,2'-indoline))](n)s [HPMAlpGP(PDMAEMA-co-PSPMA)(n)], were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of the DMAEMA and the SPMA using hyperbranched PMAlpGP as a macro RAFT agent. In aqueous solution, the copolymers self-assembled to form core-shell micelles with HPMAlpGP core and PDMAEMA-co-PSPMA shell. The hydrophobic fluorescent dye nitrobenzoxadiazolyl derivative (NBD) was loaded into the spiropyran-containing micelles. The obtained micelles not only have the photochromic properties, but also modulate the fluorescence of NBD through fluorescence resonance energy transfer (FRET), which was also observed in living cells. Slight fluorescence intensity decrease of the spiropyran in merocyanine (ME) form was observed after five UV-visible light irradiation cycles. The cytotoxicity of the HPMAlpGP(PDMAEMA-co-PSPMA)(n) micelles was lower than that of 25k PEI. All the results revealed that these photoresponsive nanoparticles are a good candidate for cell imaging and may find broad applications in biological areas such as biological diagnosis, imaging, and detection. PMID:22759087

  4. Hyperbranched PEG-based supramolecular nanoparticles for acid-responsive targeted drug delivery.

    PubMed

    Chen, Xiaofei; Yao, Xuemei; Wang, Chunran; Chen, Li; Chen, Xuesi

    2015-06-01

    Herein, hyperbranched poly(ethylene glycol)-based supramolecular nanoparticles with pH-sensitive properties were designed and used for targeted drug delivery. Via host-guest recognition between benzimidazole anchored poly(ethylene glycol)-hyperbranched polyglycerol (PEG-HPG-BM) and folic acid modified CD (FA-CD), targeted supramolecular nanoparticles (TSNs) were fabricated. At neutral aqueous conditions TSNs could load the model drug DOX. While under intracellular acidic conditions the loaded-drug would be released due to the protonation of BM. This protonation allowed the supramolecular nanoparticles to expand or even disassemble, which showes the pH-dependent property. The introduction of the active targeting FA molecule and the specific interactions with the receptor of HeLa cells means that DOX-loaded TSNs show a significantly improved anticancer efficacy. In vitro drug release assays and intracellular experiments confirmed that TSNs had an obvious pH-sensitive property and remarkably improved anticancer effects, which hold great potential for further biomedical applications such as anticancer drug delivery. PMID:26221847

  5. Succinate Functionalization of Hyperbranched Polyglycerol-Coated Magnetic Nanoparticles as a Draw Solute During Forward Osmosis.

    PubMed

    Yang, Hee-Man; Choi, Hye Min; Jang, Sung-Chan; Han, Myeong Jin; Seo, Bum-Kyoung; Moon, Jei-Kwon; Lee, Kune-Woo

    2015-10-01

    Hyperbranched polyglycerol-coated magnetic nanoparticles (SHPG-MNPs) were functionalized with succinate groups to form a draw solute for use in a forward osmosis (FO). After the one-step synthesis of hyperbranched polyglycerol-coated magnetic nanoparticles (HPG-MNPs), the polyglycerol groups on the surfaces of the HPG-MNPs were functionalized with succinic anhydride moieties. The resulting SHPG-MNPs showed no change of size and magnetic property compared with HPG-MNPs and displayed excellent dispersibility in water up to the concentration of 400 g/L. SHPG-MNPs solution showed higher osmotic pressure than that of HPG-MNPs solution due to the presence of surface carboxyl groups in SHPG-MNPs and could draw water from a feed solution across an FO membrane without any reverse draw solute leakage during FO process. Moreover, the water flux remained nearly constant over several SHPG-MNP darw solute regeneration cycles applied to the ultrafiltration (UF) process. The SHPG-MNPs demonstrate strong potential for use as a draw solute in FO processes. PMID:26726503

  6. Hyperbranched epoxy/MWCNT-CuO-nystatin nanocomposite as a high performance, biocompatible, antimicrobial material

    NASA Astrophysics Data System (ADS)

    Barua, Shaswat; Chattopadhyay, Pronobesh; Phukan, Mayur M.; Konwar, Bolin K.; Karak, Niranjan

    2014-12-01

    Hyperbranched epoxy MWCNT-CuO-nystatin nanocomposite has been presented here as an advanced antimicrobial high performance material. The material showed significant improvement of mechanical properties (tensile strength from 38 to 63 MPa) over the pristine matrix without effecting elongation. MWCNT was modified by a non-ionic surfactant, triton X-100, wherein copper oxide nanoparticles were anchored in situ by a ‘green’ method. Further, sonochemical immobilization of nystatin enhanced the stability of the system. The immobilized nanohybrid system was incorporated into the hyperbranched matrix in 1, 2 and 3 wt%. The resultant system proved its ability to prevent bacterial, fungal and microalgal fouling against the tested strains, Staphylococcus aureus, Candida albicans and Chlorella sp. Additionally, this system is quite compatible with rat heart cells. Furthermore, in vivo assessment showed that this could be utilized as an implantable antimicrobial biomaterial. Thus, the overall study pointed out that the prepared material may have immense utility in marine industry as well as in biomedical domain to address microbial fouling, without inducing any toxicity to higher organisms.

  7. Controlled synthesis of hyper-branched inorganic nanocrystals withrich three-dimensional structures

    SciTech Connect

    Kanaras, Antonios G.; Sonnichsen, Carsten; Liu, Haitao; Alivisatos, A. Paul

    2005-07-27

    Studies of crystal growth kinetics are tightly integrated with advances in the creation of new nanoscale inorganic building blocks and their functional assemblies 1-11. Recent examples include the development of semiconductor nanorods which have potential uses in solar cells 12-17, and the discovery of a light driven process to create noble metal particles with sharp corners that can be used in plasmonics 18,19. In the course of studying basic crystal growth kinetics we developed a process for preparing branched semiconductor nanocrystals such as tetrapods and inorganic dendrimers of precisely controlled generation 20,21. Here we report the discovery of a crystal growth kinetics regime in which a new class of hyper-branched nanocrystals are formed. The shapes range from 'thorny balls', to tree-like ramified structures, to delicate 'spider net'-like particles. These intricate shapes depend crucially on a delicate balance of branching and extension. The multitudes of resulting shapes recall the diverse shapes of snowflakes 22.The three dimensional nature of the branch points here, however, lead to even more complex arrangements than the two dimensionally branched structures observed in ice. These hyper-branched particles not only extend the available three-dimensional shapes in nanoparticle synthesis ,but also provide a tool to study growth kinetics by carefully observing and modeling particle morphology.

  8. Synthesis of New Hyperbranched α-Glucans from Sucrose by Lactobacillus reuteri 180 Glucansucrase Mutants.

    PubMed

    Meng, Xiangfeng; Dobruchowska, Justyna M; Pijning, Tjaard; Gerwig, Gerrit J; Dijkhuizen, Lubbert

    2016-01-20

    α-Glucans produced by glucansucrase enzymes of lactic acid bacteria attract strong attention as novel ingredients and functional biopolymers in the food industry. In the present study, α-helix 4 amino acid residues D1085, R1088, and N1089 of glucansucrase GTF180 of Lactobacillus reuteri 180 were targeted for mutagenesis both jointly and separately. Analysis of the mutational effects on enzyme function revealed that all D1085 and R1088 mutants catalyzed the synthesis of hyperbranched α-glucans with 15-22% branching (α1→3,6) linkages, compared to 13% in the wild-type GTF180. In addition, besides native (α1→6) and (α1→3) linkages, all of the mutations introduced a small amount of (α1→4) linkages (5% at most) in the polysaccharides produced. We conclude that α-helix 4 residues, especially D1085 and R1088, constituting part of the +2 acceptor binding subsite, are important determinants for the linkage specificity. The new hyperbranched α-glucans provide very interesting structural diversities and may find applications in the food industry. PMID:26688101

  9. Hyperbranched Aliphatic Polyester Modified Activated Carbon Particles with Homogenized Surface Groups

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Zhang, Liuxue

    The hyperbranched aliphatic polyester grafted activated carbon (HAPE-AC), was successfully prepared by the simple "one-pot" method. The surface functional groups of commercial activated carbon particles were homogenized to hydroxyl groups by being oxidized with nitric acid and then reduced with lithium tetrahydroaluminate (LiAlH4) at first. Secondly, the surface hydroxyl groups were used as the active sites for the solution polycondensation of the AB2 monomer, 2, 2-bis(hydroxymethyl)propionic acid (bis-MPA), with the catalysis of p-toluenesulfonic acid (p-TSA). The homogenization of the surface groups of the activated carbon particles and the graft polymerization of the hyperbranched aliphatic polyester were investigated by X-ray photoelectron spectroscopy (XPS) technique. The products were also characterized with Fourier transform infrared (FT-IR) and scanning electron microscope (SEM). The competitive adsorption properties of the products toward the heavy metal ions (Cu(II), Hg(II), Zn(II), and Cd(II)) also proved the translations of the surface groups.

  10. Biocompatible high performance hyperbranched epoxy/clay nanocomposite as an implantable material.

    PubMed

    Barua, Shaswat; Dutta, Nipu; Karmakar, Sanjeev; Chattopadhyay, Pronobesh; Aidew, Lipika; Buragohain, Alak K; Karak, Niranjan

    2014-04-01

    Polymeric biomaterials are in extensive use in the domain of tissue engineering and regenerative medicine. High performance hyperbranched epoxy is projected here as a potential biomaterial for tissue regeneration. Thermosetting hyperbranched epoxy nanocomposites were prepared with Homalomena aromatica rhizome oil-modified bentonite as well as organically modified montmorillonite clay. Fourier transformed infrared spectroscopy, x-ray diffraction and scanning and transmission electron microscopic techniques confirmed the strong interfacial interaction of clay layers with the epoxy matrix. The poly(amido amine)-cured thermosetting nanocomposites exhibited high mechanical properties like impact resistance (>100 cm), scratch hardness (>10 kg), tensile strength (48-58 MPa) and elongation at break (11.9-16.6%). Cytocompatibility of the thermosets was found to be excellent as evident by MTT and red blood cell hemolytic assays. The nanocomposites exhibited antimicrobial activity against Staphylococcus aureus (ATCC 11632), Escherichia coli (ATCC 10536), Mycobacterium smegmatis (ATCC14468) and Candida albicans (ATCC 10231) strains. In vivo biocompatibility of the best performing nanocomposite was ascertained by histopathological study of the brain, heart, liver and skin after subcutaneous implantation in Wistar rats. The material supported the proliferation of dermatocytes without induction of any sign of toxicity to the above organs. The adherence and proliferation of cells endorse the nanocomposite as a non-toxic biomaterial for tissue regeneration. PMID:24495981

  11. The in vitro biocompatibility of self-assembled hyperbranched copolyphosphate nanocarriers.

    PubMed

    Liu, Jinyao; Huang, Wei; Pang, Yan; Zhu, Xinyuan; Zhou, Yongfeng; Yan, Deyue

    2010-07-01

    Polymeric micelles are recognized as very promising nanocarriers for small-molecule drugs, DNA, and proteins delivery. Polyphosphates are an important class of eminent biomaterials and widely used in biomedicine due to their good biocompatibility, biodegradability, and flexibility in adjusting the pendant structures. Here, some full-polyphosphate nanocarriers have been constructed successfully through self-assembly of amphiphilic hyperbranched multiarm copolymers (denoted as HPHEEP-star-PPEPs). The hydrophilic core and hydrophobic multiarm of HPHEEP-star-PPEPs are composed by hyperbranched and linear polyphosphates respectively. HPHEEP-star-PPEPs can self-assembly into nanocarriers in aqueous media with controlled size from 48 to 74 nm by conveniently adjusting the length of hydrophobic arm. These nanocarriers possess excellent biocompatibility against NIH 3T3 cells and are easily internalized by vivid cells. Chlorambucil-loaded nanocarriers were investigated for proliferation inhibition of an MDA-MB-231 breast cancer cell line in vitro, and the chlorambucil dose required for 50% cellular growth inhibition was found to be 3 microg/mL. PMID:20417961

  12. Antimocrobial Polymer

    DOEpatents

    McDonald, William F.; Huang, Zhi-Heng; Wright, Stacy C.

    2005-09-06

    A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The composition comprises a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, (ii) an antimicrobial agent selected from quaternary ammonium compounds, gentian violet compounds, substituted or unsubstituted phenols, biguanide compounds, iodine compounds, and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one embodiment, the polymer is a polyamide formed from a maleic anhydride or maleic acid ester monomer and alkylamines thereby producing a polyamide having amino substituted alkyl chains on one side of the polyamide backbone; the crosslinking agent is a phosphine having the general formula (A)3P wherein A is hydroxyalkyl; and the antimicrobial agent is chlorhexidine, dimethylchlorophenol, cetyl pyridinium chloride, gentian violet, triclosan, thymol, iodine, and mixtures thereof.

  13. Antimicrobial Polymer

    DOEpatents

    McDonald, William F.; Wright, Stacy C.; Taylor, Andrew C.

    2004-09-28

    A polymeric composition having antimicrobial properties and a process for rendering the surface of a substrate antimicrobial are disclosed. The polymeric composition comprises a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, (ii) an antimicrobial agent selected from metals, metal alloys, metal salts, metal complexes and mixtures thereof, and (iii) a crosslinking agent containing functional groups capable of reacting with the amino groups. In one example embodiment, the polymer is a polyamide formed from a maleic anhydride or maleic acid ester monomer and alkylamines thereby producing a polyamide having amino substituted alkyl chains on one side of the polyamide backbone; the crosslinking agent is a phosphine having the general formula (A).sub.3 P wherein A is hydroxyalkyl; and the metallic antimicrobial agent is selected from chelated silver ions, silver metal, chelated copper ions, copper metal, chelated zinc ions, zinc metal and mixtures thereof.

  14. Non-enzymatic glucose biosensor based on hyperbranched pine-like gold nanostructure.

    PubMed

    Heli, H; Amirizadeh, O

    2016-06-01

    Hyperbranched pine-like gold nanostructure was electrodeposited on the polycrystalline gold surface at 0 mV (vs. AgCl) with the assistance of histidine as a soft template. The nanostructure was then applied as a highly sensitive nonenzymatic sensor for glucose. The catalytic activity and sensitivity of the gold nanostructure toward the electrooxidation of glucose was excellent without surface fouling and deterioration effects. The current related to the oxidation of glucose rapidly and linearly depended on its concentration with a sensitivity of 776.8 μA cm(-2)mmol(-1)dm(3), a detection limit of 3.39 μmol dm(-3) with a relative standard deviation of 2.32%. PMID:27040206

  15. Hyperbranched quasi-1D TiO2 nanostructure for hybrid organic-inorganic solar cells.

    PubMed

    Ghadirzadeh, Ali; Passoni, Luca; Grancini, Giulia; Terraneo, Giancarlo; Li Bassi, Andrea; Petrozza, Annamaria; Di Fonzo, Fabio

    2015-04-15

    The performance of hybrid solar cells is strongly affected by the device morphology. In this work, we demonstrate a poly(3-hexylthiophene-2,5-diyl)/TiO2 hybrid solar cell where the TiO2 photoanode comprises an array of tree-like hyperbranched quasi-1D nanostructures self-assembled from the gas phase. This advanced architecture enables us to increase the power conversion efficiency to over 1%, doubling the efficiency with respect to state of the art devices employing standard mesoporous titania photoanodes. This improvement is attributed to several peculiar features of this array of nanostructures: high interfacial area; increased optical density thanks to the enhanced light scattering; and enhanced crystallization of poly(3-hexylthiophene-2,5-diyl) inside the quasi-1D nanostructure. PMID:25822757

  16. Suitability of hyperbranched polyester for sensoric applications--investigation with reflectometric interference spectroscopy.

    PubMed

    Belge, Georg; Beyerlein, Detlev; Betsch, Carmen; Eichhorn, Klaus-J; Gauglitz, Günter; Grundke, Karina; Voit, Brigitte

    2002-10-01

    Hyperbranched polyesters (HBP) with different end groups (P-OH, P-COOH, P-OAc) were prepared as thin films. Their surface properties were investigated using zeta potential and contact angle measurements. The differences in surface properties between P-OH and P-COOH, on the one hand, and P-OAc, on the other hand, predicted different behavior in sensoric applications. Therefore, the vapor of the homologous series of alcohols from methanol to pentanol was exposed to the thin films. Changes in thickness were observed with reflectometric interference spectroscopy (RIfS). First investigations in a current analytical problem for the detection and discrimination of refrigerants (freons) using P-OH as sensitive layer have been shown. Polydimethylsiloxane (PDMS) and poly(ether urethane) (PUT) were used as reference sensor materials for the RIfS measurements. PMID:12373386

  17. Multidimensional Polycation β-Cyclodextrin Polymer as an Effective Aqueous Binder for High Sulfur Loading Cathode in Lithium-Sulfur Batteries.

    PubMed

    Zeng, Fanglei; Wang, Weikun; Wang, Anbang; Yuan, Keguo; Jin, Zhaoqing; Yang, Yu-sheng

    2015-12-01

    Although the lithium-sulfur battery has attracted significant attention because of its high theoretical energy density and low cost of elemental sulfur, its real application is still hindered by multiple challenges, especially the polysulfides shuttled between the cathode and anode electrodes. By originating from β-cyclodextrin and introducing a quaternary ammonium cation into β-cyclodextrin polymer, a new multifunctional aqueous polycation binder (β-CDp-N(+)) for the sulfur cathode is obtained. The unique hyperbranched network structure of the new binder β-CDp-N(+) as well as its multidimensional noncovalent interactions and the introduced cations endowed β-CDp-N(+) with some new abilities: a sulfur-electrode-stabilized ability, a polysulfides-immobilized ability, and a volume-accommodated ability, which help to ease the primary problems of the lithium-sulfur battery, i.e., the shuttle of polysulfides and the volume change of the sulfur during charge and discharge. It is demonstrated that cycling performance and rate capability of the cathodes can be the improved by using β-CDp-N(+) as the binder compared to other well-known binders. Even with high sulfur loading of 5.5 mg cm(-2), the cathode with β-CDp-N(+) still can deliver an areal capacity of 4.4 mAh cm(-2) at 50 mA g(-1) after 45 cycles, which is much higher than that achieved using the cathode with the conventional binder (0.9 mAh cm(-2)). PMID:26517299

  18. Controlled Synthesis of Uniform Cobalt Phosphide Hyperbranched Nanocrystals Using Tri-n-octylphosphine Oxide as a Phosphorus Source

    SciTech Connect

    Zhang, Haitao; Ha, Don-Hyung; Hovden, Robert; Fitting Kourkoutis, Lena; Robinson, Richard D.

    2011-01-12

    A new method to produce hyperbranched Co{sub 2}P nanocrystals that are uniform in size, shape, and symmetry was developed. In this reaction tri-n-octylphosphine oxide (TOPO) was used as both a solvent and a phosphorus source. The reaction exhibits a novel monomer-saturation-dependent tunability between Co metal nanoparticle (NP) and Co{sub 2}P NP products. The morphology of Co{sub 2}P can be controlled from sheaflike structures to hexagonal symmetric structures by varying the concentration of the surfactant. This unique product differs significantly from other reported hyperbranched nanocrystals in that the highly anisotropic shapes can be stabilized as the majority shape (>84%). This is the first known use of TOPO as a reagent as well as a coordinating background solvent in NP synthesis.

  19. Controlled synthesis of uniform cobalt phosphide hyperbranched nanocrystals using tri-n-octylphosphine oxide as a phosphorus source.

    PubMed

    Zhang, Haitao; Ha, Don-Hyung; Hovden, Robert; Kourkoutis, Lena Fitting; Robinson, Richard D

    2011-01-12

    A new method to produce hyperbranched Co(2)P nanocrystals that are uniform in size, shape, and symmetry was developed. In this reaction tri-n-octylphosphine oxide (TOPO) was used as both a solvent and a phosphorus source. The reaction exhibits a novel monomer-saturation-dependent tunability between Co metal nanoparticle (NP) and Co(2)P NP products. The morphology of Co(2)P can be controlled from sheaflike structures to hexagonal symmetric structures by varying the concentration of the surfactant. This unique product differs significantly from other reported hyperbranched nanocrystals in that the highly anisotropic shapes can be stabilized as the majority shape (>84%). This is the first known use of TOPO as a reagent as well as a coordinating background solvent in NP synthesis. PMID:21141992

  20. Cyclic and multicyclic polymers by three-dimensional polycondensation.

    PubMed

    Kricheldorf, Hans R

    2009-08-18

    The recent confirmation that polycondensations (and other step-growth polymerizations) of difunctional monomers involve cyclization reactions at any concentration and at any stage of the polymerization also has consequences for three-dimensional polycondensations on multifunctional monomers. It is demonstrated that tree-shaped (hyperbranched) oligomers are gradually transformed into star-shaped polymers with a cyclic core, when the conversion increases. Polycondensations of "a(2) + b(3)" or "a(2) + b(4)" monomer combinations yield multicyclic polymers, when gelation can be avoided. This new architecture may be subdivided into three groups: perfect multicycles free of functional groups, multicycles having b functions, and multicycles having "a" groups. The concrete examples discussed in this Account mainly concern polyethers and polyesters. PMID:19391620

  1. Single-Crystalline Hyperbranched Nanostructure of Iron Hydroxyl Phosphate Fe5(PO4)4(OH)3·2H2O for Highly Selective Capture of Phosphopeptides

    PubMed Central

    Chen, Qun; Wei, Chengzhen; Zhang, Yizhou; Pang, Huan; Lu, Qingyi; Gao, Feng

    2014-01-01

    Single-crystalline hyperbranched nanostructures of iron hydroxyl phosphate Fe5(PO4)4(OH)3·2H2O (giniite) with orthorhombic phase were synthesized through a simple route. They have a well-defined dendrite fractal structure with a pronounced trunk and highly ordered branches. The toxicity test shows that the hyperbranched nanostructures have good biocompatibility and low toxicity level, which makes them have application potentials in life science. The study herein demonstrated that the obtained hyperbranched giniite nanostructures show highly selective capture of phosphopeptides and could be used as a kind of promising nanomaterial for the specific capture of phosphopeptides from complex tryptic digests with the detection of MALDI-TOF mass spectrometry. PMID:24435094

  2. Polymer films

    DOEpatents

    Granick, Steve; Sukhishvili, Svetlana A.

    2004-05-25

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  3. Polymer films

    DOEpatents

    Granick, Steve; Sukhishvili, Svetlana A.

    2008-12-30

    A film contains a first polymer having a plurality of hydrogen bond donating moieties, and a second polymer having a plurality of hydrogen bond accepting moieties. The second polymer is hydrogen bonded to the first polymer.

  4. Dynamics of dendritic polymers in the bulk and under confinement

    SciTech Connect

    Chrissopoulou, K.; Fotiadou, S.; Androulaki, K.; Anastasiadis, S. H.; Tanis, I.; Karatasos, K.; Prevosto, D.; Labardi, M.; Frick, B.

    2014-05-15

    The structure and dynamics of a hyperbranched polyesteramide (Hybrane® S 1200) polymer and its nanocomposites with natural montmorillonite (Na{sup +}-MMT) are investigated by XRD, DSC, QENS, DS and Molecular Dynamics (MD) simulation. In bulk, the energy-resolved elastically scattered intensity from the polymer exhibits two relaxation steps, one attributed to sub-T{sub g} motions and one observed at temperatures above the glass transition, T{sub g}. The QENS spectra measured over the complete temperature range are consistent with the elastic measurements and can be correlated to the results emerging from the detailed description afforded by the atomistic simulations, which predict the existence of three relaxation processes. Moreover, dielectric spectroscopy shows the sub- T{sub g} beta process as well as the segmental relaxation. For the nanocomposites, XRD reveals an intercalated structure for all hybrids with distinct interlayer distances due to polymer chains residing within the galleries of the Na{sup +}-MMT. The polymer chains confined within the galleries show similarities in the behavior with that of the polymer in the bulk for temperatures below the bulk polymer T{sub g}, whereas they exhibit frozen dynamics under confinement at temperatures higher than that.

  5. Synthesis and supramolecular assembly of biomimetic polymers

    NASA Astrophysics Data System (ADS)

    Marciel, Amanda Brittany

    A grand challenge in materials chemistry is the synthesis of macromolecules and polymers with precise shapes and architectures. Polymer microstructure and architecture strongly affect the resulting functionality of advanced materials, yet understanding the static and dynamic properties of these complex macromolecules in bulk has been difficult due to their inherit polydispersity. Single molecule studies have provided a wealth of information on linear flexible and semi-flexible polymers in dilute solutions. However, few investigations have focused on industrially relevant complex topologies (e.g., star, comb, hyperbranched polymers) in industrially relevant solution conditions (e.g., semi-dilute, concentrated). Therefore, from this perspective there is a strong need to synthesize precision complex architectures for bulk studies as well as complex architectures compatible with current single molecule techniques to study static and dynamic polymer properties. In this way, we developed a hybrid synthetic strategy to produce branched polymer architectures based on chemically modified DNA. Overall, this approach enables control of backbone length and flexibility, as well as branch grafting density and chemical identity. We utilized a two-step scheme based on enzymatic incorporation of non-natural nucleotides containing bioorthogonal dibenzocyclooctyne (DBCO) functional groups along the main polymer backbone, followed by copper-free "click" chemistry to graft synthetic polymer branches or oligonucleotide branches to the DNA backbone, thereby allowing for the synthesis of a variety of polymer architectures, including three-arm stars, H-polymers, graft block copolymers, and comb polymers for materials assembly and single molecule studies. Bulk materials properties are also affected by industrial processing conditions that alter polymer morphology. Therefore, in an alternative strategy we developed a microfluidic-based approach to assemble highly aligned synthetic

  6. Functional Hyperbranched Polylysine as Potential Contrast Agent Probes for Magnetic Resonance Imaging.

    PubMed

    Zu, Guangyue; Liu, Min; Zhang, Kunchi; Hong, Shanni; Dong, Jingjin; Cao, Yi; Jiang, Bin; Luo, Liqiang; Pei, Renjun

    2016-06-13

    Researchers have never stopped questing contrast agents with high resolution and safety to overcome the drawbacks of small-molecule contrast agents in clinic. Herein, we reported the synthesis of gadolinium-based hyperbranched polylysine (HBPLL-DTPA-Gd), which was prepared by thermal polymerization of l-lysine via one-step polycondensation. After conjugating with folic acid, its potential application as MRI contrast agent was then evaluated. This contrast agent had no obvious cytotoxicity as verified by WST assay and H&E analysis. Compared to Gd(III)-diethylenetriaminepentaacetic acid (Gd-DTPA) (r1 = 4.3 mM(-1) s(-1)), the FA-HBPLL-DTPA-Gd exhibited much higher longitudinal relaxivity value (r1 = 13.44 mM(-1) s(-1)), up to 3 times higher than Gd-DTPA. The FA-HBPLL-DTPA-Gd showed significant signal intensity enhancement in the tumor region at various time points and provided a long time window for MR examination. The results illustrate that FA-HBPLL-DTPA-Gd will be a potential candidate for tumor-targeted MRI. PMID:27187578

  7. New core-shell hyperbranched chitosan-based nanoparticles as optical sensor for ammonia detection.

    PubMed

    El-Sherbiny, Ibrahim M; Hefnawy, Amr; Salih, Ehab

    2016-05-01

    In this paper, preparation of new core-shell amino-terminated hyperbranched chitosan nanoparticles (HBCs-NH2) NPs is described. The synthesized nanoparticles were characterized using ninhydrin assay, FTIR, TGA, and FESEM. The newly prepared (HBCs-NH2) NPs were then used as a platform for facile and controlled synthesis of silver nanoparticles (AgNPs) which was confirmed using FTIR, UV-vis spectrometry, X-ray diffraction, SEM and HRTEM. Formation of the AgNPs was also noted upon changing the color of (HBCs-NH2) NPs suspension from colorless into yellow as well as through the appearance of surface plasmon resonance (SPR) peak at 400nm. HRTEM showed a uniform and spherical morphology of the resulting HBCs-NH2 NPs with average size 400nm, and the AgNPs were formed mainly on their surface with average size of 20-50nm. The newly developed (HBCs-NH2) NPs-AgNPs showed a great potential as optical sensor for efficient detection of the ammonia concentration in solutions based on the change in the SPR. PMID:26851206

  8. Hyperbranched polyglycidol assisted green synthetic protocols for the preparation of multifunctional metal nanoparticles.

    PubMed

    Li, Haiqing; Jo, Jung Kyu; Zhang, Li Dong; Ha, Chang-Sik; Suh, Hongsuk; Kim, Il

    2010-12-01

    Biocompatible hyperbranched polyglycidol (HBP) has been demonstrated to be an effective reducing and stabilizing agent for the synthesis of highly water-soluble monometallic (Au, Ag, Pt, Pd, and Ru) and bimetallic (Au/Pt, Au/Pd, and Au/Ru) nanoparticles (NPs), which provides a general and green protocol to fabricate metal NPs. The HBP-assisted reduction of metal ions follows an analogous polyol process. The reduction reaction rate increases sharply by increasing the temperature and the molecular weight of HBP. The size of NPs is controllable simply by changing the concentration of the metal precursor. High molecular weight HBP is favorable for the formation of NPs with uniform size and improved stability. By utilizing hydroxyl groups in the HBP-passivation layer of Au NPs, TiO(2)/Au, GeO(2)/Au, and SiO(2)/Au nanohybrids are also fabricated via sol-gel processes, which sets a typical example for the creation of versatile metal NPs/inorganic oxide hybrids based on the as-prepared multifunctional NPs. PMID:21047097

  9. Tailored hybrid hyperbranched polyglycidol-silica nanocomposites with high third-order nonlinearity

    NASA Astrophysics Data System (ADS)

    Postnova, Irina; Bezverbny, Alexander; Golik, Sergey; Kulchin, Yury; Li, Haiqing; Wang, Jing; Kim, Il; Ha, Chang-Sik; Shchipunov, Yury

    2012-07-01

    One of the most convenient techniques for optical material fabrication is the sol-gel processing. It can be performed at low temperature that enables one to entrap even relatively unstable organic substances into silica matrix at the nanometer scale, thus developing homogeneous hybrid organic-inorganic nanocomposite materials of various functionalities. Here, novel hybrid organic-inorganic nanocomposites with good optical transparency and high third-order nonlinearity were prepared biomimetically through the mineralization of dendritic macromolecules (hyperbranched polyglycidols) using a compatible ethylene glycol-containing silica precursor. The synthesis was performed at neutral pH media in aqueous solutions without addition of organic solvents at ambient conditions owing to the catalysis of processing. Polyglycidols provided also the formation of gold nanoparticles localized in their core. They served as reducing and stabilizing agents. It is shown that trace amounts of nanoparticles could regulate nonlinear properties of a nanocomposite. High nonlinearity manifests itself in a supercontinuum generation at remarkably short lengths ca. 1 mm. The phenomenon consists of filamentous intense white lighting due to the spectral broadening of initial ultrashort (femtosecond) laser pulses propagating through the material. The developed hybrid nanocomposites possessing large nonlinearity, high-speed optical response, stability under intense lighting, low-cost, and easy preparation are promising for a diverse range of applications as active components for all-optical signal processing from chemical sensing to biological cell imaging and lighting control in telecommunication.

  10. Hyperbranched Polyester Hydrogels with Controlled Drug Release and Cell Adhesion Properties

    PubMed Central

    Zhang, Hongbin; Patel, Alpesh; Gaharwar, Akhilesh K.; Mihaila, Silvia M.; Iviglia, Giorgio; Mukundan, Shilpaa; Bae, Hojae; Yang, Huai; Khademhosseini, Ali

    2013-01-01

    Hyperbranched polyesters (HPE) have a high efficiency to encapsulate bioactive agents, including drugs, genes and proteins, due to their globe-like nanostructure. However, the use of these highly branched polymeric systems for tissue engineering applications has not been broadly investigated. Here, we report synthesis and characterization of photocrosslinkable HPE hydrogels with sustained drug release characteristics for cellular therapies. These HPE can encapsulate hydrophobic drug molecules within the HPE cavities, due to the presence of hydrophobic inner structure that is otherwise difficult to achieve in conventional hydrogels. The functionalization of HPE with photocrosslinkable acrylate moieties renders the formation of hydrogels with highly porous interconnected structure, and mechanically tough network. The compressive modulus of HPE hydrogels was tunable by changing the crosslinking density. The feasibility of using these HPE networks for cellular therapies was investigated by evaluating cell adhesion, spreading and proliferation on hydrogel surface. Highly crosslinked and mechanically stiff HPE hydrogels have higher cell adhesion, spreading, proliferation compared to soft and complaint HPE hydrogels. Overall, we showed that hydrogels made from HPE could be used for biomedical applications that require control cell adhesion and control release of hydrophobic clues. PMID:23394067

  11. A novel potential biocompatible hyperbranched polyspermine for efficient lung cancer gene therapy.

    PubMed

    Xie, Rong-Lin; Jang, Yoon-Jeong; Xing, Lei; Zhang, Bing-Feng; Wang, Feng-Zhen; Cui, Peng-Fei; Cho, Myung-Haing; Jiang, Hu-Lin

    2015-01-15

    The clinical successful application of gene therapy critically depends upon the development of non-toxic and efficient delivery system. Although polycationic non-viral vectors hold great promise in nanomedicine, the exploring of application in clinics still remains a big challenge. To develop a non-toxic and efficient non-viral gene delivery system, two kinds of endogenous substance, citric acid (CA) and spermine (SPE), were used to prepare a new low charge density hyperbranched polyspermine (HPSPE) by one-pot polymerization. The biocompatibility evaluated by hemolytic activity and red blood cell (RBC) aggregation indicated that HPSPE was highly biocompatible without causing hemolysis and RBC aggregation compared with PEI as well as SPE. The MTS assay also demonstrated that the cell viability of HPSPE was above 90% even at 200 μg/mL at different time (24 and 72 h), which much higher than PEI 25K. Besides, HPSPE showed high transfection efficiency without any toxic effect after aerosol delivery to the mice. Moreover, aerosol delivery of HPSPE/Akt1 shRNA significantly reduced tumor size and numbers and efficiently suppressed lung tumorigenesis ultimately in K-ras(LA1) lung cancer model mice. These results suggest that low charge density as well as endogenous substance skeleton endow HPSPE with great potential for toxicity-free and efficient gene therapy. PMID:25448566

  12. Multivalent anchored and crosslinked hyperbranched polyglycerol monolayers as antifouling coating for titanium oxide surfaces.

    PubMed

    Wei, Qiang; Krysiak, Stefanie; Achazi, Katharina; Becherer, Tobias; Noeske, Paul-Ludwig Michael; Paulus, Florian; Liebe, Hendrik; Grunwald, Ingo; Dernedde, Jens; Hartwig, Andreas; Hugel, Thorsten; Haag, Rainer

    2014-10-01

    A set of new catecholic monolayer coatings was developed to improve the antifouling performance of TiO2 surfaces. To solve the problem of the weak charge-transfer interaction between a single catechol anchor and TiO2, multiple catechol groups were combined with hyperbranched polyglycerol (hPG) which is a distinct dendritic scaffold that exposes its multivalent anchor groups on the surface. Thus, multivalent catecholic hPGs can be easily prepared for surface modification. The immobilization of the compounds was monitored by quartz crystal microbalance with dissipation monitoring. Surface properties of the coatings were analyzed by water contact angle, X-ray photoelectron spectroscopy, and atomic force microscopy. The antifouling ability and stability were investigated by protein adsorption and cell adhesion. By increasing the number of catechol groups on the hPG scaffold, the stability and surface coverage could be significantly enhanced. Moreover, the inner-layer crosslinking of the coatings by grafting and initiating vinyl groups clearly improved their long-term stability. As a result, hPG with a catecholic functional degree of 10% (hPG-Cat10) and hPG with both catecholic and vinylic functional degree of 5% (hPG-Cat5-V5) were identified as the best catecholic hPGs to prepare bioinert and stable monolayer coatings on TiO2. PMID:25189471

  13. Thermal properties of poly(urethane-ester-siloxane)s based on hyperbranched polyester

    NASA Astrophysics Data System (ADS)

    Pergal, M. V.; Džunuzović, J. V.; Kićanović, M.; Vodnik, V.; Pergal, M. M.; Jovanović, S.

    2011-12-01

    Novel polyurethanes (PUs) were synthesized using hydroxy-terminated hyperbranched polyester (BH-20) and 4,4'-methylenediphenyl diisocyanate (MDI) as hard segments and hydroxy-terminated ethylene oxide-poly(dimethylsiloxane)-ethylene oxide triblock copolymer (PDMS-EO) as soft segment, with soft segment content ranging from 30 to 60 wt %. The PUs were synthesized by two-step solution polymerization method. The influence of the soft segment content on the structure, swelling behavior and thermal properties of PUs was investigated. According to the results obtained by swelling measurements, the increase of the hard segment content resulted in the increase of the crosslinking density of synthesized samples. DSC results showed that the glass transition temperatures increase from 36 to 65°C with increasing hard segment content. It was demonstrated using thermogravimetric analysis (TGA) that thermal stability of investigated PUs increases with increase of the soft PDMS-EO content. This was concluded from the temperatures corresponding to the 10 wt % loss, which represents the beginning of thermal degradation of samples.

  14. Nanostructured polymer membranes for proton conduction

    DOEpatents

    Balsara, Nitash Pervez; Park, Moon Jeong

    2013-06-18

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

  15. Sequentially Hetero-functional, Topological Polymers by Step-growth Thiol-yne Approach

    NASA Astrophysics Data System (ADS)

    Han, Jin; Zheng, Yaochen; Zhao, Bo; Li, Sipei; Zhang, Yuanchao; Gao, Chao

    2014-03-01

    Sequence-controlled polymers (SCPs) such as DNA and proteins play an important role in biology. Many efforts have been devoted to synthesize SCPs in the past half a century. However, to our knowledge, the artificial sequences containing independently functional groups have never been reported. Here, we present a facile and scalable approach based on radical-initiated step-growth polymerization to synthesize sequence-controlled functional polymers (SCFPs) with various topologies, covering from linear to random and hyperbranched polymers. The functional groups, such as OH/NH2, OH/COOH, and NH2/N3, alternately arranged along the chain, which were further selectively functionalized to achieve DNA-mimic and hetero-multifunctional SCPs. This user-friendly strategy exhibits advantages of commercially available monomers, catalyst-free process, fast reaction, high yield and water solvent, opening a general approach to facile and scalable synthesis of SCFPs.

  16. Sequentially Hetero-functional, Topological Polymers by Step-growth Thiol-yne Approach

    PubMed Central

    Han, Jin; Zheng, Yaochen; Zhao, Bo; Li, Sipei; Zhang, Yuanchao; Gao, Chao

    2014-01-01

    Sequence-controlled polymers (SCPs) such as DNA and proteins play an important role in biology. Many efforts have been devoted to synthesize SCPs in the past half a century. However, to our knowledge, the artificial sequences containing independently functional groups have never been reported. Here, we present a facile and scalable approach based on radical-initiated step-growth polymerization to synthesize sequence-controlled functional polymers (SCFPs) with various topologies, covering from linear to random and hyperbranched polymers. The functional groups, such as OH/NH2, OH/COOH, and NH2/N3, alternately arranged along the chain, which were further selectively functionalized to achieve DNA-mimic and hetero-multifunctional SCPs. This user-friendly strategy exhibits advantages of commercially available monomers, catalyst-free process, fast reaction, high yield and water solvent, opening a general approach to facile and scalable synthesis of SCFPs. PMID:24633000

  17. Biocompatible Polymer/Quantum Dots Hybrid Materials: Current Status and Future Developments

    PubMed Central

    Shen, Lei

    2011-01-01

    Quantum dots (QDs) are nanometer-sized semiconductor particles with tunable fluorescent optical property that can be adjusted by their chemical composition, size, or shape. In the past 10 years, they have been demonstrated as a powerful fluorescence tool for biological and biomedical applications, such as diagnostics, biosensing and biolabeling. QDs with high fluorescence quantum yield and optical stability are usually synthesized in organic solvents. In aqueous solution, however, their metallic toxicity, non-dissolubility and photo-luminescence instability prevent the direct utility of QDs in biological media. Polymers are widely used to cover and coat QDs for fabricating biocompatible QDs. Such hybrid materials can provide solubility and robust colloidal and optical stability in water. At the same time, polymers can carry ionic or reactive functional groups for incorporation into the end-use application of QDs, such as receptor targeting and cell attachment. This review provides an overview of the recent development of methods for generating biocompatible polymer/QDs hybrid materials with desirable properties. Polymers with different architectures, such as homo- and co-polymer, hyperbranched polymer, and polymeric nanogel, have been used to anchor and protect QDs. The resulted biocompatible polymer/QDs hybrid materials show successful applications in the fields of bioimaging and biosensing. While considerable progress has been made in the design of biocompatible polymer/QDs materials, the research challenges and future developments in this area should affect the technologies of biomaterials and biosensors and result in even better biocompatible polymer/QDs hybrid materials. PMID:24956449

  18. Electroactive polymers for sensing.

    PubMed

    Wang, Tiesheng; Farajollahi, Meisam; Choi, Yeon Sik; Lin, I-Ting; Marshall, Jean E; Thompson, Noel M; Kar-Narayan, Sohini; Madden, John D W; Smoukov, Stoyan K

    2016-08-01

    Electromechanical coupling in electroactive polymers (EAPs) has been widely applied for actuation and is also being increasingly investigated for sensing chemical and mechanical stimuli. EAPs are a unique class of materials, with low-moduli high-strain capabilities and the ability to conform to surfaces of different shapes. These features make them attractive for applications such as wearable sensors and interfacing with soft tissues. Here, we review the major types of EAPs and their sensing mechanisms. These are divided into two classes depending on the main type of charge carrier: ionic EAPs (such as conducting polymers and ionic polymer-metal composites) and electronic EAPs (such as dielectric elastomers, liquid-crystal polymers and piezoelectric polymers). This review is intended to serve as an introduction to the mechanisms of these materials and as a first step in material selection for both researchers and designers of flexible/bendable devices, biocompatible sensors or even robotic tactile sensing units. PMID:27499846

  19. Light-triggered reversible "one-to-two" morphological transition in a "latent double-amphiphilic" linear-hyperbranched supramolecular block copolymer.

    PubMed

    Jiang, Wenfeng; Liu, Yong; Yu, Chunyang; Li, Shanlong; Li, Yongjin; Zhou, Yongfeng

    2016-07-01

    This study reports a new category of stimuli-responsive morphological transitions, i.e., from one morphology (e.g., vesicles) to another two different ones (e.g., nanosheets and nanofibers), by investigating the light-responsive self-assembly behaviour of a "latent double-amphiphilic" linear-hyperbranched supramolecular block copolymer. PMID:27211799

  20. Ru(II) Tris(3,8-Dibromo-1,10-Phenanthro1ine): A New Versatile Core for the Divergent Synthesis of Hyperbranched Systems

    NASA Technical Reports Server (NTRS)

    Sotiriou-Leventis, Chariklia; Yang, Jinhua; Duan, Penggao; Leventis, Nicholas

    2004-01-01

    We report the first synthesis of Ru(II) tris(3,8-dibromo-1,lO-phenanthroline) bishexafluorophosphate, and we demonstrate its utility as a building core for the divergent synthesis of hyperbranched systems by coupling with phenylacetylene in the preparation of Rum tris(3,8-diphenylethynyl- 1,lO-phenanthroline) dihexafluorophosphate.

  1. Triggered and catalyzed self-assembly of hyperbranched DNA structures for logic operations and homogeneous CRET biosensing of microRNA.

    PubMed

    Bi, Sai; Yue, Shuzhen; Wu, Qiang; Ye, Jiayan

    2016-04-01

    Toehold-mediated strand displacement-based nanocircuits are developed by integrating catalytic hairpin assembly (CHA) with hybridization chain reaction (HCR), which achieves self-assembly of hyperbranched DNA structures and is readily utilized as an enzyme-free amplifier for homogeneous CRET detection of microRNA with high sensitivity and selectivity. PMID:27010350

  2. A polymer-Triton X-100 conjugate capable of PH-dependent red blood cell lysis: a model system illustrating the possibility of drug delivery within acidic intracellular compartments.

    PubMed

    Duncan, R; Ferruti, P; Sgouras, D; Tuboku-Metzger, A; Ranucci, E; Bignotti, F

    1994-01-01

    Poly(amidoamines) are soluble polymers containing tertiary amino and amido groups regularly arranged along the macromolecular chain, and their net average charge alters considerably as pH changes from neutral to acidic leading to a change in conformation. This property provides the possibility to design polymer-drug conjugates that are, following intravenous administration, relatively compacted and thus protect a drug payload in the circulation, but following pinocytic internalisation into acidic intracellular compartments unfold permitting pH-triggered intracellular drug delivery. To study the feasibility of this approach, a covalent conjugate of a poly(amidoamine) (MBI) was prepared to contain the membrane lytic non-ionic detergent Triton X-100 (as a model), and its ability to lyse red blood cells in vitro was used as an indicator of conjugate conformation at at different pHs. Although Triton X-100 was highly lytic at pH 5.5, 7.4 and 8.0, and the parent polymer MBI was not lytic under any conditions, the conjugate only showed concentration-dependent red blood cell lysis at pH 5.5. Moreover, incubation of human leukaemic cells (CCRF) with these substrates showed conjugate to be more toxic than MBI (IC50 values of 100 micrograms/ml and 650 micrograms/ml respectively) and less toxic than Triton X-100 (IC50 of 1 microgram/ml). PMID:7858959

  3. Antimicrobial hyperbranched poly(ester amide)/polyaniline nanofiber modified montmorillonite nanocomposites.

    PubMed

    Pramanik, Sujata; Bharali, Pranjal; Konwar, B K; Karak, Niranjan

    2014-02-01

    There has been growing interest in the use of nanomaterials featuring potent of antimicrobial activity in the biomedical domain. It still remains a challenge for the researchers to develop an efficient nanocomposite possessing antimicrobial efficacy against broad spectrum microbes including bacteria, fungi as well as algal consortium, posing serious challenges for the human survival. In addressing the above problem, we report the fabrication of bio-based hyperbranched poly(ester amide) (HBPEA)/polyaniline nanofiber modified montmorillonite (MMT) nanocomposites by an ex-situ polymerization technique at varied weight percentages (1, 2.5, 5 wt.%) of the modified MMT (nanohybrid). The Fourier transform infrared spectroscopy confirmed the structural changes upon interaction of the nanohybrid with HBPEA. A probable mechanism is proposed for the formation of nanocomposites with partially exfoliated nanoplatelet structure, which was further confirmed from the high resolution transmission electron microscopic analyses. The prepared nanocomposites exhibited potent efficacy against gram positive bacteria like Bacillus subtilis and Staphylococcus aureus as compared to the gram negative ones like Pseudomonas aeruginosa and Escherichia coli. The nanocomposites showed significant antifungal activity against Aspergillus niger, Fusarium oxysporum and Coleotricum capcii and antialgal activity against algal consortium comprising of Chlorella, Hormidium and Cladophorella species. The formation of thermosetting nanocomposites resulted in the acceptable improvement of desired physico-chemical and mechanical properties including thermostability. Thus pronounced antimicrobial activity of the nanocomposites against a spectrum of bacterial and fungal strains as well as a consortium of algal species along with other desired performance vouched them as potent antimicrobial materials in the realm of health and biomedical industry. PMID:24411352

  4. Design Considerations for Developing Hyperbranched Polyglycerol Nanoparticles as Systemic Drug Carriers.

    PubMed

    Wong, Nelson K Y; Misri, Ripen; Shenoi, Rajesh A; Chafeeva, Irina; Kizhakkedathu, Jayachandran N; Khan, Mohamed K

    2016-05-01

    PEGylation is commonly used to increase the plasma residence time of anticancer drug nanocarriers. However, PEGylation may trigger antibody production and lead to accelerated blood clearance in subsequent administrations. Moreover, the presence of PEG shells on nanocarriers may also hamper endosomal escape and decrease drug payload release. To avoid these shortcomings, we synthesized and evaluated a non-PEGylated, hyperbranched polyglycerol nanoparticle (HPG NP) with a hydrophobic core and a hydrophilic HPG shell, HPG-C10-HPG, as a candidate for systemic delivery of anticancer drug. In vitro studies with primary human cell lines revealed that HPG-C10-HPG possesses low cytotoxicity. The presence of long chain alkyl groups (C1o) in the core as the hydrophobic pocket in the NP enabled the binding and sustained release of the hydrophobic drug docetaxel. Remarkably, the docetaxel-loaded HPG-C10-HPG formulation also confers preferential protection to primary cells, when compared to cancer cells, potentially widening the therapeutic index. HPG-C10-HPG, however, accumulated at higher levels in the liver and spleen when administered intravenously in mice. Comparing the biodistribution patterns of HPG-C10-HPG, PEGylated HPG-C10-PEG, and unmodified HPG in a xenograft model reveals that the accumulation pattern of HPG-C10-HPG was attributed to insufficient shielding of the hydrophobic groups by the HPG shell. Our results revealed the influence of the nature of the hydrophilic shell and the presence of hydrophobic groups on the tumor-to-tissue accumulation specificities of these HPG NP variants. Therefore, the present study provides insights into the structural considerations of future HPG NP designs for systemic drug delivery. PMID:27305828

  5. Hydrotropic polymeric mixed micelles based on functional hyperbranched polyglycerol copolymers as hepatoma-targeting drug delivery system.

    PubMed

    Zhang, Xuejiao; Zhang, Xinge; Yu, Peien; Han, Yucai; Li, Yangguang; Li, Chaoxing

    2013-01-01

    Mixed copolymer nanoparticles (NPs) self-assembled from β-cyclodextrin-grafted hyperbranched polyglycerol (HPG-g-CD) and lactobionic acid (LA)-grafted hyperbranched polyglycerol (HPG-g-LA) were applied as carriers for a hydrophobic antitumor drug, paclitaxel (PTX), achieving hepatocellular carcinoma-targeted delivery. The resulting NPs exhibited high drug loading capacity and substantial stability in aqueous solution. In vitro drug release studies demonstrated a controlled drug release profile with increased release at acidic pH. Remarkably, tumor proliferation assays showed that PTX-loaded mixed copolymer NPs inhibited asialoglycoprotein (ASGP) receptor positive HepG2 cell proliferation in a concentration-dependent manner in comparison with ASGP receptor negative BGC-823 cells. Moreover, the competition assay demonstrated that the small molecular LA inhibited the cellular uptake of the PTX-loaded mixed copolymer NPs, indicating the ASGP receptor-mediated endocytosis in HepG2 cells. In addition, the intracellular uptake tests by confocal laser scanning microscopy showed that the mixed copolymer NPs were more efficiently taken up by HepG2 cells compared with HPG-g-CD NPs. These results suggest a feasible application of the mixed copolymer NPs as nanocarriers for hepatoma-targeted delivery of potent antitumor drugs. PMID:23132353

  6. Poly(carbonate-imide) polymer

    NASA Technical Reports Server (NTRS)

    St. Clair, Terry L. (Inventor); Maudgal, Shubha (Inventor); Pratt, J. Richard (Inventor)

    1987-01-01

    A novel series of polymers and copolymers based on a polyimide backbone with the incorporation of carbonate moieties along the backbone. The process for preparing these polymers and copolymers is also disclosed as is a novel series of dinitrodiphenyl carbonates and diaminodiphenyl carbonates. The novel polymers and copolymers exhibit high temperature capability and because of the carbonate unit, many exhibit a high degree of order and/or crystallinity.

  7. A comparative study of three ternary complexes prepared in different mixing orders of siRNA/redox-responsive hyperbranched poly (amido amine)/hyaluronic acid

    PubMed Central

    Chen, Cheng-Jun; Zhao, Zhi-Xia; Wang, Jian-Cheng; Zhao, En-Yu; Gao, Ling-Yan; Zhou, Shu-Feng; Liu, Xiao-Yan; Lu, Wan-Liang; Zhang, Qiang

    2012-01-01

    In this study, a novel redox-responsive hyperbranched poly(amido amine) (named PCD) was synthesized and used as a cationic polymer to form a ternary complex with small interfering RNA (siRNA) and hyaluronic acid (HA) for siRNA delivery. Here, it is hypothesized that different mixing orders result in different assembly structures, which may affect the siRNA delivery efficiency. To investigate the effects of mixing orders on siRNA delivery efficiency in two human breast cancer cell lines, three ternary complexes with different mixing orders of siRNA/PCD/HA were prepared and characterized: mixing order I (initially prepared siRNA/PCD binary complex further coated by negatively charged HA), mixing order II ( initially prepared HA/PCD binary complex further incubated with siRNA), and mixing order III ( initially prepared siRNA/HA mixture further electrostatically compacted by positively charged PCD). With an optimized siRNA/PCD/HA charge ratio of 1/20/16, the particle sizes and zeta potentials of these ternary complexes were 124.8 nm and 27.3 mV (mixing order I), 147.5 nm and 29.9 mV (mixing order II), and 128.8 nm and 19.4 mV (mixing order III). Also, the effects on stability, cellular uptake, and gene silencing efficiency of siRNA formulated in ternary complexes with different mixing orders were investigated. The results showed that mixing orders I and III displayed better siRNA transfection and protection than mixing order II in human breast cancer MCF-7 and MDA-MB-231 cells. More interesting, at the siRNA/PCD/HA charge ratio of 1/20/16, the gene silencing effects on vascular endothelial growth factor expression in MDA-MB- 231 cells were as follows: mixing order III > mixing order I > mixing order II. Based on these results, a likely explanation for the difference in functionality dependent on mixing orders is the formation of different assembly structures. These results may help future optimization of siRNA ternary complexes for achieving better delivery

  8. Polymers for Drug Delivery Systems

    PubMed Central

    Liechty, William B.; Kryscio, David R.; Slaughter, Brandon V.; Peppas, Nicholas A.

    2012-01-01

    Polymers have played an integral role in the advancement of drug delivery technology by providing controlled release of therapeutic agents in constant doses over long periods, cyclic dosage, and tunable release of both hydrophilic and hydrophobic drugs. From early beginnings using off-the-shelf materials, the field has grown tremendously, driven in part by the innovations of chemical engineers. Modern advances in drug delivery are now predicated upon the rational design of polymers tailored for specific cargo and engineered to exert distinct biological functions. In this review, we highlight the fundamental drug delivery systems and their mathematical foundations and discuss the physiological barriers to drug delivery. We review the origins and applications of stimuli-responsive polymer systems and polymer therapeutics such as polymer-protein and polymer-drug conjugates. The latest developments in polymers capable of molecular recognition or directing intracellular delivery are surveyed to illustrate areas of research advancing the frontiers of drug delivery. PMID:22432577

  9. Microgravity Polymers

    NASA Technical Reports Server (NTRS)

    1986-01-01

    A one-day, interactive workshop considering the effects of gravity on polymer materials science was held in Cleveland, Ohio, on May 9, 1985. Selected programmatic and technical issues were reviewed to introduce the field to workshop participants. Parallel discussions were conducted in three disciplinary working groups: polymer chemistry, polymer physics, and polymer engineering. This proceedings presents summaries of the workshop discussions and conclusions.

  10. Novel polymers and method of preparing same

    NASA Technical Reports Server (NTRS)

    Hirshfield, S. M. (Inventor)

    1973-01-01

    Polymers are prepared with terminal functional groups by reacting a compound selected from the group consisting of lithium p-lithiophenoxide and tetrabutylammonium p-lithiophenoxide as an initiator with material such as butadiene. The resulting functionally terminated new polymers are then capable of reacting with coupling agents to form star polymers.

  11. Metal-Organic-Framework-Templated Polyelectrolyte Nanocapsules for the Encapsulation and Delivery of Small-Molecule-Polymer Conjugates.

    PubMed

    Liu, Shuo; Chen, Jianbin; Bao, Xiaojia; Li, Tao; Ling, Yunyang; Li, Chunxiang; Wu, Chuanliu; Zhao, Yibing

    2016-06-21

    Herein, we report a strategy for exploiting nanoscale metal-organic frameworks (nano-MOFs) as templates for the layer-by-layer (LbL) assembly of polyelectrolytes. Because small-molecule drugs or imaging agents cannot be efficiently encapsulated by polyelectrolyte nanocapsules, we investigated two promising and biocompatible polymers (comb-shaped polyethylene glycol (PEG) and hyperbranched polyglycerol-based PEG) for the conjugation of model drugs and imaging agents, which were then encapsulated inside the nano-MOF-templated nanocapsules. Furthermore, we also systemically explored the release kinetics of the encapsulated conjugates, and examined how the encapsulation and/or release processes could be controlled by varying the composition and architecture of the polymers. We envision that our nano-MOFs-templated nanocapsules, through combining with small-molecule-polymer conjugates, will represent a new type of delivery system that could open up new opportunities for biomedical applications. PMID:27123998

  12. Electroactive polymers for sensing

    PubMed Central

    2016-01-01

    Electromechanical coupling in electroactive polymers (EAPs) has been widely applied for actuation and is also being increasingly investigated for sensing chemical and mechanical stimuli. EAPs are a unique class of materials, with low-moduli high-strain capabilities and the ability to conform to surfaces of different shapes. These features make them attractive for applications such as wearable sensors and interfacing with soft tissues. Here, we review the major types of EAPs and their sensing mechanisms. These are divided into two classes depending on the main type of charge carrier: ionic EAPs (such as conducting polymers and ionic polymer–metal composites) and electronic EAPs (such as dielectric elastomers, liquid-crystal polymers and piezoelectric polymers). This review is intended to serve as an introduction to the mechanisms of these materials and as a first step in material selection for both researchers and designers of flexible/bendable devices, biocompatible sensors or even robotic tactile sensing units. PMID:27499846

  13. Supramolecular dendritic polymers: from synthesis to applications.

    PubMed

    Dong, Ruijiao; Zhou, Yongfeng; Zhu, Xinyuan

    2014-07-15

    CONSPECTUS: Supramolecular dendritic polymers (SDPs), which perfectly combine the advantages of dendritic polymers with those of supramolecular polymers, are a novel class of non-covalently bonded, highly branched macromolecules with three-dimensional globular topology. Because of their dynamic/reversible nature, unique topological structure, and exceptional physical/chemical properties (e.g., low viscosity, high solubility, and a large number of functional terminal groups), SDPs have attracted increasing attention in recent years in both academic and industrial fields. In particular, the reversibility of non-covalent interactions endows SDPs with the ability to undergo dynamic switching of structure, morphology, and function in response to various external stimuli, such as pH, temperature, light, stress, and redox agents, which further provides a flexible and robust platform for designing and developing smart supramolecular polymeric materials and functional supramolecular devices. The existing SDPs can be systematically classified into the following six major types according to their topological features: supramolecular dendrimers, supramolecular dendronized polymers, supramolecular hyperbranched polymers, supramolecular linear-dendritic block copolymers, supramolecular dendritic-dendritic block copolymers, and supramolecular dendritic multiarm copolymers. These different types of SDPs possess distinct morphologies, unique architectures, and specific functions. Benefiting from their versatile topological structures as well as stimuli-responsive properties, SDPs have displayed not only unique characteristics or advantages in supramolecular self-assembly behaviors (e.g., controllable morphologies, specific performance, and facile functionalization) but also great potential to be promising candidates in various fields. In this Account, we summarize the recent progress in the synthesis, functionalization, and self-assembly of SDPs as well as their potential

  14. Secondary polymer layered impregnated tile

    NASA Technical Reports Server (NTRS)

    Tran, Huy K. (Inventor); Rasky, Daniel J. (Inventor); Szalai, Christine E. (Inventor); Carroll, Joseph A. (Inventor); Hsu, Ming-ta S. (Inventor)

    2005-01-01

    A low density organic polymer impregnated preformed fibrous ceramic article includes a plurality of layers. A front layer includes ceramic fibers or carbon fibers or combinations of ceramic fibers and carbon fibers, and is impregnated with an effective amount of at least one organic polymer. A middle layer includes polymer impregnated ceramic fibers. A back layer includes ceramic fibers or carbon fibers or combinations of ceramic fibers and carbon fibers, and is impregnated with an effective amount of at least one low temperature pyrolyzing organic polymer capable of decomposing without depositing residues.

  15. Post polymerization cure shape memory polymers

    DOEpatents

    Wilson, Thomas S; Hearon, Michael Keith; Bearinger, Jane P

    2014-11-11

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  16. Tandem mass spectrometry and ion mobility mass spectrometry for the analysis of molecular sequence and architecture of hyperbranched glycopolymers

    PubMed Central

    Liu, Xiumin; Cool, Lydia R.; Lin, Kenneth; Kasko, Andrea M.; Wesdemiotis, Chrys

    2015-01-01

    Multidimensional mass spectrometry techniques, combining matrix-assisted laser desorption/ionization (MALDI) or electrospray ionization (ESI) with tandem mass spectrometry (MS2), multistage mass spectrometry (MSn) or ion mobility mass spectrometry (IM-MS), have been employed to gain precise structural insight on the compositions, sequences and architectures of small oligomers of a hyperbranched glycopolymer, prepared by atom transfer radical copolymerization of an acrylate monomer (A) and an acrylate inimer (B), both carrying mannose ester pendants. The MS data confirmed the incorporation of multiple inimer repeat units, which ultimately lead to the hyperbranched material. The various possible structures of n-mers with the same composition were subsequently elucidated based on MS2 and MSn studies. The characteristic elimination of bromomethane molecule provided definitive information about the comonomer connectivity in the copolymeric AB2 trimer and A2B2 tetramer, identifying as present only one of the three possible trimeric isomers (viz. sequence BBA) and only two of the six possible tetrameric isomers (viz. sequences BBA2 and BABA). Complementary IM-MS studies confirmed that only one of the tetrameric structures is formed. Comparison of the experimentally determined collision cross-section of the detected isomer with those predicted by molecular simulations for the two possible sequences ascertained BBA2 as the predominant tetrameric architecture. The multidimensional MS approaches presented provide connectivity information at the atomic level without requiring high product purity (due to the dispersive nature of MS) and, hence, should be particularly useful for the microstructure characterization of novel glycopolymers and other types of complex copolymers. PMID:25519163

  17. Preparation of water-soluble hyperbranched polyester nanoparticles with sulfonic acid functional groups and their micelles behavior, anticoagulant effect and cytotoxicity.

    PubMed

    Han, Qiaorong; Chen, Xiaohan; Niu, Yanlian; Zhao, Bo; Wang, Bingxiang; Mao, Chun; Chen, Libin; Shen, Jian

    2013-07-01

    Biocompatibility of nanoparticles has been attracting great interest in the development of nanoscience and nanotechnology. Herein, the aliphatic water-soluble hyperbranched polyester nanoparticles with sulfonic acid functional groups (HBPE-SO3 NPs) were synthesized and characterized. They are amphiphilic polymeric nanoparticles with hydrophobic hyperbranched polyester (HBPE) core and hydrophilic sulfonic acid terminal groups. Based on our observations, we believe there are two forms of HBPE-SO3 NPs in water under different conditions: unimolecular micelles and large multimolecular micelles. The biocompatibility and anticoagulant effect of the HBPE-SO3 NPs were investigated using coagulation tests, hemolysis assay, morphological changes of red blood cells (RBCs), complement and platelet activation detection, and cytotoxicity (MTT). The results confirmed that the sulfonic acid terminal groups can substantially enhance the anticoagulant property of HBPE, and the HBPE-SO3 NPs have the potential to be used in nanomedicine due to their good bioproperties. PMID:23718279

  18. Piezoelectric Polymers

    NASA Technical Reports Server (NTRS)

    Harrison, J. S.; Ounaies, Z.; Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    The purpose of this review is to detail the current theoretical understanding of the origin of piezoelectric and ferroelectric phenomena in polymers; to present the state-of-the-art in piezoelectric polymers and emerging material systems that exhibit promising properties; and to discuss key characterization methods, fundamental modeling approaches, and applications of piezoelectric polymers. Piezoelectric polymers have been known to exist for more than forty years, but in recent years they have gained notoriety as a valuable class of smart materials.

  19. Investigations of non-linear polymers as high performance lubricant additives

    SciTech Connect

    Robinson, Joshua W.; Bhattacharya, Priyanka; Qu, Jun; Bays, J. Timothy; Cosimbescu, Lelia

    2015-03-22

    Off-the-shelf available engine oils contain an assortment of additives that increase the performance of base oils and maximize the overall efficiency of the machine. With ever increasing requirements for fuel efficiency, the demand for novel materials that outperform older generations is also on the rise. One approach towards increasing overall efficiency is to reduce internal friction and wear in an engine. From an additive approach, this is typically achieved by altering the bulk oil’s viscosity at high temperatures via polymers. In general, the hydrodynamic volume of polymers increase (expand) at elevated temperatures and decrease (contract/deflate) with declining temperatures and this effect is enhanced be carefully designing specific structures and architectures. The natural thinning tendency of base oil with increasing temperatures is in part mitigated by the expansion of the macromolecules added, and the overall effect is decreasing the viscosity losses at high temperatures. Traditional polymer architectures vary from linear to dendritic, where linear polymers of the same chemical composition and molecular weight to its dendritic counterpart will undergo a more significant free volume change in solution with regards to temperature changes. This advantage has been exploited in the literature towards the production of viscosity modifiers. However, one major disadvantage of linear polymers is degradation due to mechanical shear forces and high temperatures causing a shorter additive lifetime. Dendrimers on the other hand are known to demonstrate superior robustness to shear degradation when compared to their respective linear counterparts. An additional advantage of the dendritic architecture is the ability to tailor the peripheral end-groups towards influencing polymer-solvent and/or polymer-surface interactions. Comb-burst hyperbranched polymers are a hybrid of the aforementioned architectures and provide several compromises between the traditional

  20. Thermally tunable polymer microlenses

    NASA Astrophysics Data System (ADS)

    Huang, Xian; Cheng, Chao-Min; Wang, Li; Wang, Bin; Su, Chih-Chuan; Ho, Mon-Shu; LeDuc, Philip R.; Lin, Qiao

    2008-06-01

    Polymer microlenses capable of using heat to control its focal length are presented. The microlenses are created by exposing droplets of the polymer SU-8 to UV light. By altering the temperature of the microlenses via on-chip heating, their curvature and focal length are actively controlled without mechanical movements. By directly and indirectly measuring temperature-dependent changes of the focal length, we test the ability of the microlenses as a tunable imaging component. The microlenses have potential use in applications such as laser systems, functional biomimetics, and endoscopy.

  1. Computer modeling of polymers

    NASA Technical Reports Server (NTRS)

    Green, Terry J.

    1988-01-01

    A Polymer Molecular Analysis Display System (p-MADS) was developed for computer modeling of polymers. This method of modeling allows for the theoretical calculation of molecular properties such as equilibrium geometries, conformational energies, heats of formations, crystal packing arrangements, and other properties. Furthermore, p-MADS has the following capabilities: constructing molecules from internal coordinates (bonds length, angles, and dihedral angles), Cartesian coordinates (such as X-ray structures), or from stick drawings; manipulating molecules using graphics and making hard copy representation of the molecules on a graphics printer; and performing geometry optimization calculations on molecules using the methods of molecular mechanics or molecular orbital theory.

  2. Polymer nanostructures synthesized by controlled living polymerization for tumor-targeted drug delivery.

    PubMed

    Wang, Christine E; Stayton, Patrick S; Pun, Suzie H; Convertine, Anthony J

    2015-12-10

    The development of drug delivery systems based on well-defined polymer nanostructures could lead to significant improvements in the treatment of cancer. The design of these therapeutic nanosystems must account for numerous systemic and circulation obstacles as well as the specific pathophysiology of the tumor. Nanoparticle size and surface charge must also be carefully selected in order to maintain long circulation times, allow tumor penetration, and avoid clearance by the reticuloendothelial system (RES). Targeting ligands such as vitamins, peptides, and antibodies can improve the accumulation of nanoparticle-based therapies in tumor tissue but must be optimized to allow for intratumoral penetration. In this review, we will highlight factors influencing the design of nanoparticle therapies as well as the development of modern controlled "living" polymerization techniques (e.g. ATRP, RAFT, ROMP) that are leading to the creation of sophisticated new polymer architectures with discrete spatially-defined functional modules. These innovative materials (e.g. star polymers, polymer brushes, macrocyclic polymers, and hyperbranched polymers) combine many of the desirable properties of traditional nanoparticle therapies while substantially reducing or eliminating the need for complex formulations. PMID:26342661

  3. Dendritic polymer-based nanodevices for targeted drug delivery applications

    NASA Astrophysics Data System (ADS)

    Kannan, R. M.; Kolhe, Parag; Gurdag, Sezen; Khandare, Jayant; Lieh-Lai, Mary

    2004-03-01

    Dendrimers and hyperbranched polymers are unimolecular micellar nanostructures, characterized by globular shape ( ˜ 20 nm) and large density of functional groups at periphery. The tailorable end groups make them ideal for conjugation with drugs, ligands, and imagining agents, making them an attractive molecular nanodevices for drug delivery. Compared to linear polymers and nanoparticles, these nanodevices enter cells rapidly, carrying drugs and delivering them inside cells. Performance of nanodevices prepared for asthma and cancer drug delivery will be discussed. Our conjugation procedure produced very high drug payloads. Dendritic polymer-drug conjugates were very effective in transporting methotrexate (a chemotherapy drug) into both sensitive (CCRF-CEM cell line) and resistant cell line (CEM-MTX). The conjugate nanodevice was 3 times more effective than free drug in the sensitive line, and 9 times more effective in the resistant cell line (based on IC50). The physics of cell entry and drug release from these nanodevices are being investigated. The conjugates appear to enter cells through endocytosis, with the rate of entry dependent on end-group, molecular weight, the pH of the medium, and the cancerous nature of the cells.

  4. Testing and technical capabilities

    SciTech Connect

    Morrow, R.W.; Dill, M.S.

    1984-05-01

    Capabilities of the following are outlined: state-of-the-art-services, measurement control and capabilities coordination, sampling and standard section, analytical technology section, environmental-industrial hygiene section, spectrochemical section, inorganic and production control section, instrumentation and control section, instrument technology, and mass spectrometry-isotopic section.

  5. Capability and Deliberation

    ERIC Educational Resources Information Center

    Hinchliffe, Geoffrey

    2009-01-01

    This paper explores the role of deliberation in the context of the capability approach to human well-being from the standpoint of the individual doing the reflecting. The concept of a "strong evaluator" is used develop a concept of the agent of capability. The role of values is discussed in the process of deliberating, particularly the nature of…

  6. XRCF Testing Capabilities

    NASA Technical Reports Server (NTRS)

    Reily, Cary; Kegely, Jeff; Burdine, Robert (Technical Monitor)

    2001-01-01

    The Space Optics Manufacturing Technology Center's X-ray Calibration Facility has been recently modified to test Next Generation Space Telescope (NGST) developmental mirrors at cryogenic temperatures (35 degrees Kelvin) while maintaining capability for performance testing of x-ray optics and detectors. The facility's current cryo-optical testing capability and potential modifications for future support of NGST will be presented.

  7. Widening Participation; Widening Capability

    ERIC Educational Resources Information Center

    Walker, Melanie

    2008-01-01

    This paper proposes that widening participation in higher education might distinctively be conceptualised beyond economically driven human capital outcomes, as a matter of widening capability. Specifically, the paper proposes forming the capability of students to become and to be "strong evaluators", able to make reflexive and informed choices…

  8. Metrology measurement capabilities

    SciTech Connect

    Shroyer, K.

    1997-02-01

    Since 1958, the AlliedSignal Federal Manufacturing and Technologies (FM and T) Metrology Department has developed measurement technology and calibration capability in four major areas of measurement: (1) mechanical; (2) environmental, gas, liquid; (3) electrical (D.C., A.C., RF/Microwave); and (4) optical and radiation. The capabilities developed include unique capabilities in many areas of measurement and engineering expertise to develop measurement techniques and resolve measurement problems in these major areas. A strong audit function has been developed to provide a means to evaluate the calibration programs of the suppliers and internal calibration organizations. This evaluation includes measurement audits and technical surveys. The requirements placed on metrology require traceability of measurements to the National Institute of Standards and Technology or to nationally recognized methods or natural phenomena. A description of Metrology capabilities, traceability flow charts, and the measurement uncertainty of each of the measurement capabilities is contained in the report.

  9. Optimizing the Acid Catalyzed Synthesis of Hyperbranched Poly(Glycerol-diacids) Oligomers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oligomeric pre-polymers were synthesized by the acid-catalyzed condensation of glycerol with succinic acid, glutaric acid and azelaic acid in dimethylsulfoxide (DMSO) or dimethylformamide (DMF). The prepolymers were obtained, on average in 84% yield, and were characterized by proton NMR, MALDI-TOF ...

  10. Drug structural features affect drug delivery from hyperbranched polyesteramide hot melt extrudates.

    PubMed

    Raviña-Eirin, Elena; Azuaje, Jhonny; Sotelo, Eddy; Gomez-Amoza, Jose Luis; Martinez-Pacheco, Ramon

    2016-05-01

    The aim of this study was firstly to evaluate the utility of Hybrane S1200 as a hot melt extrusion (HME) carrier to prepare instant-release multiparticulate systems for very poorly-soluble drugs such as ketoconazole or nifedipine. Hybrane S1200 allows an easy extrusion of its drug mixtures at a relatively low temperature, not higher than 90°C, and with no need of any additional aid. Extrudates containing 10% of nifedipine or ketoconazole form monophasic systems. Nifedipine extrudate shows no drug release in drug dissolution rate tests while ketoconazole extrudate release reaches only 60% of drug content. Additionally, a turbidity in the dissolution medium due to the formation of a kind of polymer vesicles (ranging 3-0.2μm in size) is observed. These facts could suggest a chemical interaction between the polymer and both drugs, triggered by the HME process. Both nifedipine and ketoconazole share characteristic acid-base profiles that could facilitate a degradation processes within the polymer, thus modifying Hybrane's water-solubility and polar nature. Such modified polymer structure, when in aqueous medium, forms the aforementioned stable vesicles that may encapsulate the drugs, thus making its delivery difficult or even preventing it. PMID:26912462

  11. Preparation of redox polymer cathodes for thin film rechargeable batteries

    DOEpatents

    Skotheim, Terje A.; Lee, Hung S.; Okamoto, Yoshiyuki

    1994-11-08

    The present invention relates to the manufacture of thin film solid state electrochemical devices using composite cathodes comprising a redox polymer capable of undergoing oxidation and reduction, a polymer solid electrolyte and conducting carbon. The polymeric cathode material is formed as a composite of radiation crosslinked polymer electrolytes and radiation crosslinked redox polymers based on polysiloxane backbones with attached organosulfur side groups capable of forming sulfur-sulfur bonds during electrochemical oxidation.

  12. Membrane consisting of polyquaternary amine ion exchange polymer network interpenetrating the chains of thermoplastic matrix polymer

    NASA Technical Reports Server (NTRS)

    Rembaum, A.; Wallace, C. J. (Inventor)

    1978-01-01

    An ion exchange membrane was formed from a solution containing dissolved matrix polymer and a set of monomers which are capable of reacting to form a polyquaternary ion exchange material; for example vinyl pyride and a dihalo hydrocarbon. After casting solution and evaporation of the volatile component's, a relatively strong ion exchange membrane was obtained which is capable of removing anions, such as nitrate or chromate from water. The ion exchange polymer forms an interpenetrating network with the chains of the matrix polymer.

  13. Tritium containing polymers having a polymer backbone substantially void of tritium

    DOEpatents

    Jensen, G.A.; Nelson, D.A.; Molton, P.M.

    1992-03-31

    A radioluminescent light source comprises a solid mixture of a phosphorescent substance and a tritiated polymer. The solid mixture forms a solid mass having length, width, and thickness dimensions, and is capable of self-support. In one aspect of the invention, the phosphorescent substance comprises solid phosphor particles supported or surrounded within a solid matrix by a tritium containing polymer. The tritium containing polymer comprises a polymer backbone which is essentially void of tritium. 2 figs.

  14. Tritium containing polymers having a polymer backbone substantially void of tritium

    DOEpatents

    Jensen, George A.; Nelson, David A.; Molton, Peter M.

    1992-01-01

    A radioluminescent light source comprises a solid mixture of a phosphorescent substance and a tritiated polymer. The solid mixture forms a solid mass having length, width, and thickness dimensions, and is capable of self-support. In one aspect of the invention, the phosphorescent substance comprises solid phosphor particles supported or surrounded within a solid matrix by a tritium containing polymer. The tritium containing polymer comprises a polymer backbone which is essentially void of tritium.

  15. KSC Technical Capabilities Website

    NASA Technical Reports Server (NTRS)

    Nufer, Brian; Bursian, Henry; Brown, Laurette L.

    2010-01-01

    This document is the website pages that review the technical capabilities that the Kennedy Space Center (KSC) has for partnership opportunities. The purpose of this information is to make prospective customers aware of the capabilities and provide an opportunity to form relationships with the experts at KSC. The technical capabilities fall into these areas: (1) Ground Operations and Processing Services, (2) Design and Analysis Solutions, (3) Command and Control Systems / Services, (4) Materials and Processes, (5) Research and Technology Development and (6) Laboratories, Shops and Test Facilities.

  16. Engineering Capabilities and Partnerships

    NASA Technical Reports Server (NTRS)

    Poulos, Steve

    2010-01-01

    This slide presentation reviews the engineering capabilities at Johnson Space Center, The presentation also reviews the partnerships that have resulted in successfully designed and developed projects that involved commercial and educational institutions.

  17. Remote Controlled Orbiter Capability

    NASA Technical Reports Server (NTRS)

    Garske, Michael; delaTorre, Rafael

    2007-01-01

    The Remote Control Orbiter (RCO) capability allows a Space Shuttle Orbiter to perform an unmanned re-entry and landing. This low-cost capability employs existing and newly added functions to perform key activities typically performed by flight crews and controllers during manned re-entries. During an RCO landing attempt, these functions are triggered by automation resident in the on-board computers or uplinked commands from flight controllers on the ground. In order to properly route certain commands to the appropriate hardware, an In-Flight Maintenance (IFM) cable was developed. Currently, the RCO capability is reserved for the scenario where a safe return of the crew from orbit may not be possible. The flight crew would remain in orbit and await a rescue mission. After the crew is rescued, the RCO capability would be used on the unmanned Orbiter in an attempt to salvage this national asset.

  18. Metrology measurement capability

    NASA Astrophysics Data System (ADS)

    Shroyer, K.

    1995-01-01

    During the past 36 years, the Kansas City Division's (KCD) Metrology Department has developed measurement technology and calibration capability in four major areas of measurement: (1) Mechanical; (2) Environmental, Gas, Liquid; Electrical (D.C., A.C., RF/Microwave); and (3) Optical and Radiation. The capabilities developed include unique capabilities in many areas of measurement and engineering expertise to develop measurement techniques and resolve measurement problems in these major areas. KCD Metrology was established in 1958 to provide a measurement base for the Kansas City Plant. The Metrology Engineering Department provides the expertise to develop measurement capabilities for virtually any type of measurement which falls into the broad areas listed above. The engineering staff currently averages almost 19 years of measurement experience. A strong audit function has been developed to provide a means to evaluate the calibration programs of our suppliers and internal calibration organizations. This evaluation includes measurement audits and technical surveys. The requirements placed on Metrology require traceability of measurements to the National Institute of Standards and Technology or to nationally recognized methods or natural phenomena. A description of Metrology capabilities, traceability flow charts, and the measurement uncertainty of each of the measurement capabilities is contained in the following pages.

  19. Metrology measurement capabilities

    SciTech Connect

    Barnes, L.M.

    1997-06-01

    Since 1958, the AlliedSignal Federal Manufacturing and Technologies (FM and T) Metrology Department has developed measurement technology and calibration capability in four major areas of measurement: mechanical; environmental, gas, liquid; electrical (D.C., A.C., RF/microwave); and optical and radiation. The capabilities developed include unique capabilities in many areas of measurement and engineering expertise to develop measurement techniques and resolve measurement problems in these major areas. FM and T Metrology was established in 1958 to provide a measurement base for the Department of energy`s Kansas City Plant. The Metrology Engineering Department provides the expertise to develop measurement capabilities for virtually any type of measurement which falls into the broad areas listed above. The engineering staff currently averages almost 16 years of measurement experience. A strong audit function has been developed to provide a means to evaluate the calibration programs of the suppliers and internal calibration organizations. This evaluation includes measurement audits and technical surveys. The requirements placed on Metrology require traceability of measurements to the National Institute of Standards and Technology or to nationally recognized methods or natural phenomena. A description of Metrology capabilities, traceability flow charts, and the measurement uncertainty of each of the measurement capabilities is contained in this report.

  20. Metrology measurement capability

    SciTech Connect

    Shroyer, K.

    1995-01-01

    During the past 36 years, the Kansas City Division`s (KCD) Metrology Department has developed measurement technology and calibration capability in four major areas of measurement: (1) Mechanical; (2) Environmental, Gas, Liquid; Electrical (D.C., A.C., RF/Microwave); and (3) Optical and Radiation. The capabilities developed include unique capabilities in many areas of measurement and engineering expertise to develop measurement techniques and resolve measurement problems in these major areas. KCD Metrology was established in 1958 to provide a measurement base for the Kansas City Plant. The Metrology Engineering Department provides the expertise to develop measurement capabilities for virtually any type of measurement which falls into the broad areas listed above. The engineering staff currently averages almost 19 years of measurement experience. A strong audit function has been developed to provide a means to evaluate the calibration programs of our suppliers and internal calibration organizations. This evaluation includes measurement audits and technical surveys. The requirements placed on Metrology require traceability of measurements to the National Institute of Standards and Technology or to nationally recognized methods or natural phenomena. A description of Metrology capabilities, traceability flow charts, and the measurement uncertainty of each of the measurement capabilities is contained in the following pages.

  1. Poly (Carbonate-Mide) Polymer

    NASA Technical Reports Server (NTRS)

    St.clair, T. L. (Inventor); Maudgal, S. (Inventor); Pratt, J. R. (Inventor)

    1986-01-01

    A novel series of polymers and copolymers based on a polymide backbone with the incorporation of carbonate moieties along the backbone is presented. The preparation process for the polymers and copolymers is disclosed together with a novel series of dinitrodiphenyl carbonates and diaminodiphenyl carbonates. The novel polyners and copolymers exhibit high temperature capability and because of the carbonate unit, many exhibit a high degree of order and/or crystallinity.

  2. Polymer Electrolytes

    NASA Astrophysics Data System (ADS)

    Hallinan, Daniel T.; Balsara, Nitash P.

    2013-07-01

    This review article covers applications in which polymer electrolytes are used: lithium batteries, fuel cells, and water desalination. The ideas of electrochemical potential, salt activity, and ion transport are presented in the context of these applications. Potential is defined, and we show how a cell potential measurement can be used to ascertain salt activity. The transport parameters needed to fully specify a binary electrolyte (salt + solvent) are presented. We define five fundamentally different types of homogeneous electrolytes: type I (classical liquid electrolytes), type II (gel electrolytes), type III (dry polymer electrolytes), type IV (dry single-ion-conducting polymer electrolytes), and type V (solvated single-ion-conducting polymer electrolytes). Typical values of transport parameters are provided for all types of electrolytes. Comparison among the values provides insight into the transport mechanisms occurring in polymer electrolytes. It is desirable to decouple the mechanical properties of polymer electrolyte membranes from the ionic conductivity. One way to accomplish this is through the development of microphase-separated polymers, wherein one of the microphases conducts ions while the other enhances the mechanical rigidity of the heterogeneous polymer electrolyte. We cover all three types of conducting polymer electrolyte phases (types III, IV, and V). We present a simple framework that relates the transport parameters of heterogeneous electrolytes to homogeneous analogs. We conclude by discussing electrochemical stability of electrolytes and the effects of water contamination because of their relevance to applications such as lithium ion batteries.

  3. Star Polymers.

    PubMed

    Ren, Jing M; McKenzie, Thomas G; Fu, Qiang; Wong, Edgar H H; Xu, Jiangtao; An, Zesheng; Shanmugam, Sivaprakash; Davis, Thomas P; Boyer, Cyrille; Qiao, Greg G

    2016-06-22

    Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings. PMID:27299693

  4. Polymer Chemistry

    NASA Technical Reports Server (NTRS)

    Williams, Martha; Roberson, Luke; Caraccio, Anne

    2010-01-01

    This viewgraph presentation describes new technologies in polymer and material chemistry that benefits NASA programs and missions. The topics include: 1) What are Polymers?; 2) History of Polymer Chemistry; 3) Composites/Materials Development at KSC; 4) Why Wiring; 5) Next Generation Wiring Materials; 6) Wire System Materials and Integration; 7) Self-Healing Wire Repair; 8) Smart Wiring Summary; 9) Fire and Polymers; 10) Aerogel Technology; 11) Aerogel Composites; 12) Aerogels for Oil Remediation; 13) KSC's Solution; 14) Chemochromic Hydrogen Sensors; 15) STS-130 and 131 Operations; 16) HyperPigment; 17) Antimicrobial Materials; 18) Conductive Inks Formulations for Multiple Applications; and 19) Testing and Processing Equipment.

  5. Space Logistics: Launch Capabilities

    NASA Technical Reports Server (NTRS)

    Furnas, Randall B.

    1989-01-01

    The current maximum launch capability for the United States are shown. The predicted Earth-to-orbit requirements for the United States are presented. Contrasting the two indicates the strong National need for a major increase in Earth-to-orbit lift capability. Approximate weights for planned payloads are shown. NASA is studying the following options to meet the need for a new heavy-lift capability by mid to late 1990's: (1) Shuttle-C for near term (include growth versions); and (2) the Advanced Lauching System (ALS) for the long term. The current baseline two-engine Shuttle-C has a 15 x 82 ft payload bay and an expected lift capability of 82,000 lb to Low Earth Orbit. Several options are being considered which have expanded diameter payload bays. A three-engine Shuttle-C with an expected lift of 145,000 lb to LEO is being evaluated as well. The Advanced Launch System (ALS) is a potential joint development between the Air Force and NASA. This program is focused toward long-term launch requirements, specifically beyond the year 2000. The basic approach is to develop a family of vehicles with the same high reliability as the Shuttle system, yet offering a much greater lift capability at a greatly reduced cost (per pound of payload). The ALS unmanned family of vehicles will provide a low end lift capability equivalent to Titan IV, and a high end lift capability greater than the Soviet Energia if requirements for such a high-end vehicle are defined.In conclusion, the planning of the next generation space telescope should not be constrained to the current launch vehicles. New vehicle designs will be driven by the needs of anticipated heavy users.

  6. Electroactive Polymer (EAP) Actuation of Mechanisms and Robotic Devices

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y.; Leary, S.; Harrison, J.; Smith, J.

    1999-01-01

    Actuators are responsible to the operative capability of manipulation systems and robots. In recent years, electroactive polymers (EAP) have emerged as potential alternative to conventional actuators.

  7. Electrochemiluminescence biosensor for ultrasensitive determination of ochratoxin A in corn samples based on aptamer and hyperbranched rolling circle amplification.

    PubMed

    Yang, Linlin; Zhang, Ying; Li, Ruibao; Lin, Cuiying; Guo, Longhua; Qiu, Bin; Lin, Zhenyu; Chen, Guonan

    2015-08-15

    Determination of ochratoxin A (OTA) is highly important for food safety control. In this study, a signal-on electrochemiluminescence (ECL) biosensor which combined the characteristics of high efficiency of hyperbranched rolling circle amplification (HRCA) and high selectivity of aptamer was developed for OTA determination. The capture probe DNA (CDNA) was firstly immobilized on the gold electrode surface through Au-S interaction, then the OTA aptamer was modified on the electrode surface through hybridization with CDNA. Since OTA can competitively bind with the aptamer due to their high affinity, which would induce the releasing of aptamer from the electrode surface. Subsequently, the free CDNA on the electrode surface can hybridize with the padlock probe and induce HRCA reaction subsequently. Thus, the HRCA products which contained large amount of double-stranded DNA (dsDNA) fragments can be accumulated on the electrode surface. Since Ru(phen)3(2+) can intercalate into the groove of dsDNA and acts as ECL indicator, high ECL intensity can be detected from the electrode surface. The enhanced ECL intensity has a linear relationship with OTA in the range of 0.05-500 pg/mL with a correlation coefficient of 0.9957, and the limit of detection (LOD) was 0.02 pg/mL. The developed biosensor has been applied to determine OTA concentration in the corn samples with satisfied results. PMID:25835519

  8. Hyperbranched polyethyleneimine induced cross-linking of polyamide-imide nanofiltration hollow fiber membranes for effective removal of ciprofloxacin.

    PubMed

    Sun, Shi Peng; Hatton, T Alan; Chung, Tai-Shung

    2011-05-01

    This study aims to develop a positively charged nanofiltration (NF) hollow fiber membrane for effective removal of ciprofloxacin from water. A novel NF membrane was fabricated by hyperbranched polyethyleneimine (PEI) induced cross-linking on a polyamide-imide hollow fiber support. The spongy-like, fully porous membrane support provides minimal transport resistance and sufficient mechanical strengths for water permeation under high pressures. It is found that the PEI modification significantly influences NF performance through the mechanisms of size exclusion, charge repulsion, and solute-membrane affinity. Specifically, after PEI induced cross-linking, the membrane pore size is significantly reduced. The membrane surface becomes more hydrophilic and positively charged. As a result of these synergic effects, the rejection of ciprofloxacin is substantially enhanced. Furthermore, experimental results show that the molecular weight of PEI has tremendous effect on NF performance of the as-modified membrane. The NF membrane modified by a high molecular weight PEI_60K exhibits the highest rejection, the lowest fouling tendency, and keeps a constant flux over the whole pH range. This study may have great potential for developing high-performance antifouling NF hollow fiber membranes for various industrial applications. PMID:21456576

  9. Adjustable bioadhesive control of PEGylated hyperbranch brushes on polystyrene microplate interface for the improved sensitivity of human blood typing.

    PubMed

    Chen, Yan-Wen; Chang, Yung; Lee, Rong-Ho; Li, Wen-Tyng; Chinnathambi, Arunachalam; Alharbi, Sulaiman Ali; Hsiue, Ging-Ho

    2014-08-01

    A PEGylated 96-well polystyrene (PS) microplate was first introduced for applications in high-throughput screening for selective blood typing to minimize the risks in blood transfusions. Herein, we present a hemocompatible PS 96-well microplate with adjustable PEGylated hyperbranch brush coverage prepared by ozone pretreated activation and thermally induced surface PEGylation. The grafting properties, hydration capacity, and blood compatibility of the PEGylated hyperbrush immobilized PS surfaces in human blood were illustrated by the combined chemical and physical properties of the surface, and the dependence of the specific absorption of human plasma fibrinogen onto the PEGylated surfaces on the grafting density was analyzed by monoclonal antibodies. The surface coverage of PEGylated brushes plays a major role in the bioadhesive properties of modified PS microplates, which in turn control the level of agglutination sensitivity in blood typing. The bioadhesive resistance toward proteins, platelets, and erythrocytes in human whole blood showed a correlation to the controlled hydration properties of the PEGylated hyperbrush-modified surfaces. Therefore, we suggested that the surface coverage of PEGylated hyperbrushes on PS surfaces can increase the sensitivity of cross-matching blood agglutination by up to 16-fold compared to that of the conventional 96-well virgin PS due to the regulated biorecognition of hematocrit and antibodies of the PEGylated hyperbrush-modified surfaces. PMID:25022949

  10. Fabrication of magnetic water-soluble hyperbranched polyol functionalized graphene oxide for high-efficiency water remediation.

    PubMed

    Hu, Lihua; Li, Yan; Zhang, Xuefei; Wang, Yaoguang; Cui, Limei; Wei, Qin; Ma, Hongmin; Yan, Liangguo; Du, Bin

    2016-01-01

    Magnetic water-soluble hyperbranched polyol functionalized graphene oxide nanocomposite (MWHPO-GO) was successfully prepared and applied to water remediation in this paper. MWHPO-GO was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), magnetization curve, zeta potential, scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses. MWHPO-GO exhibited excellent adsorption performance for the removal of synthetic dyes (methylene blue (MB) and methyl violet (MV)) and heavy metal (Pb(II)). Moreover, MWHPO-GO could be simply recovered from water with magnetic separation. The pseudo-second order equation and the Langmuir model exhibited good correlation with the adsorption kinetic and isotherm data, respectively, for these three pollutants. The thermodynamic results (ΔG < 0, ΔH < 0, ΔS < 0) implied that the adsorption process of MB, MV and Pb(II) was feasible, exothermic and spontaneous in nature. A possible adsorption mechanism has been proposed where π-π stacking interactions, H-bonding interaction and electrostatic attraction dominated the adsorption of MB/MV and chelation and electrostatic attraction dominated the adsorption of Pb(II). In addition, the excellent reproducibility endowed MWHPO-GO with the potential for application in water remediation. PMID:27354318

  11. Bio-based hyperbranched polyurethane/Fe3O4 nanocomposites: smart antibacterial biomaterials for biomedical devices and implants.

    PubMed

    Das, Beauty; Mandal, Manabendra; Upadhyay, Aadesh; Chattopadhyay, Pronobesh; Karak, Niranjan

    2013-06-01

    The fabrication of a smart magnetically controllable bio-based polymeric nanocomposite (NC) has immense potential in the biomedical domain. In this context, magneto-thermoresponsive sunflower oil modified hyperbranched polyurethane (HBPU)/Fe3O4 NCs with different wt.% of magnetic nanoparticles (Fe3O4) were prepared by an in situ polymerization technique. Fourier-transform infrared, x-ray diffraction, vibrating sample magnetometer, scanning electron microscope, transmission electron microscope, thermal analysis and differential scanning calorimetric were used to analyze various physico-chemical structural attributes of the prepared NC. The results showed good interfacial interactions between HBPU and well-dispersed superparamagnetic Fe3O4, with an average diameter of 7.65 nm. The incorporation of Fe3O4 in HBPU significantly improved the thermo-mechanical properties along with the shape-memory behavior, antibacterial activity, biocompatibility as well as biodegradability in comparison to the pristine system. The cytocompatibility of the degraded products of the NC was also verified by in vitro hemolytic activity and MTT assay. In addition, the in vivo biocompatibility and non-immunological behavior, as tested in Wistar rats after subcutaneous implantation, show promising signs for the NC to be used as antibacterial biomaterial for biomedical device and implant applications. PMID:23532037

  12. A chitosan-Au-hyperbranched polyester nanoparticles-based antifouling immunosensor for sensitive detection of carcinoembryonic antigen.

    PubMed

    Sun, Chong; Ma, Lie; Qian, Qiuhui; Parmar, Soniya; Zhao, Wenbo; Zhao, Bo; Shen, Jian

    2014-09-01

    Analysts are always interested in finding new functional nanomaterials and devices with good properties for electrochemical sensor applications. In this paper, hyperbranched polyester nanoparticles with carboxylic acid functional groups (HBPE-CA NPs) were synthesized and combined with chitosan wrapped around Au nanoparticles (CS-Au NPs) to prepare a novel and sensitive electrochemical immunosensor by adsorption of carcinoembryonic antibody (anti-CEA) on the (HBPE-CA)/CS-Au NPs modified glass carbon electrode (GCE). Under the optimized conditions, the proposed immunosensor displayed a good amperometric response to carcinoembryonic antigen (CEA). Moreover, based on the antibiofouling properties, the immunosensor could be used for the direct detection of CEA in whole blood, and exhibited a wide detection range (1-10(7) fg mL(-1)), and a low detection limit of 0.251 fg mL(-1) (signal/noise = 3). Control experiments were also carried out by using ascorbic acid (AA), uric acid (UA), human immunoglobulin G (IgG), BSA and glucose in the absence of CEA. The good stability and repeatability of this immunosensor were also proven. Importantly, the results of the detection of clinical whole blood specimens with the proposed immunosensor showed good consistency with the data determined by enzyme-linked immunosorbent assay (ELISA) in serum samples. Furthermore, the developed immunosensor could provide a promising immunoassay strategy for clinical applications, since the values we measured in whole blood directly are likely closer to the real values. PMID:24957417

  13. Investigation on the interactions between fullerene and β-CD-g-hyperbranched polyglycerol to produce water-soluble fullerene

    NASA Astrophysics Data System (ADS)

    Eskandari, Mohammad; Najdian, Atena; Soleyman, Rouhollah

    2016-06-01

    Developing a successful way to solubilize C60 in water is a longstanding, critical, and challenging issue in nanotechnology, biological, and medicine applications because of the great potential of fullerene derivatives in anti-viral therapy. In the current study, an efficient strategy for the preparing of water-soluble C60 at room temperature has been developed by complexion of C60 with hyperbranched polyglycerol linked to the β-cyclodextrin core (β-CD-g-HPG). The interactions between C60 and β-CD-g-HPG were investigated using a range of analytical techniques such as FTIR, NMR, UV-vis spectroscopy as well as visual techniques including SEM and AFM images. The particle size for a 1:2 (C60: β-CD-g-HPG) complex was also determined to be monodisperse ∼60 nm from DLS, and it was appropriately matched with the size obtained from SEM pictures. The results show our synthesized hybrid nanomaterials will hopefully find interesting applications in biomedicine.

  14. Characterization of oligosaccharide-functionalized hyperbranched poly(ethylene imine) and their complexes with retinol in aqueous solution.

    PubMed

    Bekhradnia, Sara; Naz, Iram; Lund, Reidar; Effenberg, Christiane; Appelhans, Dietmar; Sande, Sverre Arne; Nyström, Bo

    2015-11-15

    Structure, internal density distribution, and size of hyperbranched poly(ethylene imine) (PEI) functionalized with various amounts of maltose (PEI-Mal) in phosphate buffer were studied by small angle X-ray scattering (SAXS) and dynamic light scattering (DLS). The value of pH was varied in the range from 3 to 9. Virtually no effect of pH on the nanostructure was found in this interval. The SAXS results revealed a broad segmental radial density distribution, i.e. a "fluffy" globular structure rather than a distinct core-shell structure with a high-density compact core and a low-density corona. This suggests that the maltose units are rather evenly distributed both in the interior and on the surface of the species with a PEI-core of molar mass of 25,000g/mol. The DLS measurements showed that the overall size of the PEI-Mal derivatives increased as the number of maltose units in the PEI-Mal structures rises. The interaction of the hydrophobic model drug retinol with PEI or PEI-Mal derivatives was also investigated. The UV-visible spectroscopy results disclosed that the solubility of retinol in the phosphate buffer is very poor and it takes a very long time to solubilize retinol. Moreover, retinol induces aggregation of dendritic glycopolymers where the growth of aggregates occurs continuously over several days and then remains virtually constant. PMID:26218197

  15. Dissipative particle dynamics simulation study on self-assembly of amphiphilic hyperbranched multiarm copolymers with different degrees of branching.

    PubMed

    Tan, Haina; Wang, Wei; Yu, Chunyang; Zhou, Yongfeng; Lu, Zhongyuan; Yan, Deyue

    2015-11-21

    Hyperbranched multiarm copolymers (HMCs) have shown great potential to be excellent precursors in self-assembly to form various supramolecular structures in all scales and dimensions in solution. However, theoretical studies on the self-assembly of HMCs, especially the self-assembly dynamics and mechanisms, have been greatly lagging behind the experimental progress. Herein, we investigate the effect of degree of branching (DB) on the self-assembly structures of HMCs by dissipative particle dynamics (DPD) simulation. Our simulation results demonstrate that the self-assembly morphologies of HMCs can be changed from spherical micelles, wormlike micelles, to vesicles with the increase of DBs, which are qualitatively consistent with the experimental observations. In addition, both the self-assembly mechanisms and the dynamic processes for the formation of these three aggregates have been systematically disclosed through the simulations. These self-assembly details are difficult to be shown by experiments and are very useful to fully understand the self-assembly behaviors of HMCs. PMID:26364696

  16. A label-free and high sensitive aptamer biosensor based on hyperbranched polyester microspheres for thrombin detection.

    PubMed

    Sun, Chong; Han, Qiaorong; Wang, Daoying; Xu, Weimin; Wang, Weijuan; Zhao, Wenbo; Zhou, Min

    2014-11-19

    In this paper, we have synthesized hyperbranched polyester microspheres with carboxylic acid functional groups (HBPE-CA) and developed a label-free electrochemical aptamer biosensor using thrombin-binding aptamer (TBA) as receptor for the measurement of thrombin in whole blood. The indium tin oxide (ITO) electrode surface modified with HBPE-CA microspheres was grafted with TBA, which has excellent binding affinity and selectivity for thrombin. Binding of the thrombin at the modified ITO electrode surface greatly restrained access of electrons for a redox probe of [Fe(CN)6](3-/4-). Moreover, the aptamer biosensor could be used for detection of thrombin in whole blood, a wide detection range (10fM-100nM) and a detection limit on the order of 0.90fM were demonstrated. Control experiments were also carried out by using bull serum albumin (BSA) and lysozyme in the absence of thrombin. The good stability and repeatability of this aptamer biosensor were also proved. We expect that this demonstration will lead to the development of highly sensitive label-free sensors based on aptamer with lower cost than current technology. The integration of the technologies, which include anticoagulant, sensor and nanoscience, will bring significant input to high-performance biosensors relevant to diagnostics and therapy of interest for human health. PMID:25441157

  17. Fabrication of magnetic water-soluble hyperbranched polyol functionalized graphene oxide for high-efficiency water remediation

    PubMed Central

    Hu, Lihua; Li, Yan; Zhang, Xuefei; Wang, Yaoguang; Cui, Limei; Wei, Qin; Ma, Hongmin; Yan, Liangguo; Du, Bin

    2016-01-01

    Magnetic water-soluble hyperbranched polyol functionalized graphene oxide nanocomposite (MWHPO-GO) was successfully prepared and applied to water remediation in this paper. MWHPO-GO was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), magnetization curve, zeta potential, scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses. MWHPO-GO exhibited excellent adsorption performance for the removal of synthetic dyes (methylene blue (MB) and methyl violet (MV)) and heavy metal (Pb(II)). Moreover, MWHPO-GO could be simply recovered from water with magnetic separation. The pseudo-second order equation and the Langmuir model exhibited good correlation with the adsorption kinetic and isotherm data, respectively, for these three pollutants. The thermodynamic results (ΔG < 0, ΔH < 0, ΔS < 0) implied that the adsorption process of MB, MV and Pb(II) was feasible, exothermic and spontaneous in nature. A possible adsorption mechanism has been proposed where π-π stacking interactions, H-bonding interaction and electrostatic attraction dominated the adsorption of MB/MV and chelation and electrostatic attraction dominated the adsorption of Pb(II). In addition, the excellent reproducibility endowed MWHPO-GO with the potential for application in water remediation. PMID:27354318

  18. Solution-Stable Colloidal Gold Nanoparticles via Surfactant-Free, Hyperbranched Polyglycerol-b-polystyrene Unimolecular Templates.

    PubMed

    Iocozzia, James; Lin, Zhiqun

    2016-07-19

    Hyperbranched polyglycerol-block-polystyrene copolymers, denoted HPG-b-PS, are synthesized and employed as a new and effective unimolecular template for synthesizing colloidal gold (Au) nanoparticles. The coordination of noble metal precursors with polyether within the inner HPG core and subsequent in situ reduction enables the formation of well-dispersed and stable PS-capped Au nanoparticles. The inner HPG core is produced via ring opening multibranching polymerization (ROMBP) and subsequently converted into atom transfer radical polymerization (ATRP) macroinitiators for the controlled growth of polystyrene (PS) arms possessing low polydispersity (PDI < 1.31). An initial investigation into the templating parameters of HPG-b-PS was undertaken by producing templates with different arm numbers (98 and 117) and different PS chain lengths (i.e., molecular weight = 3500-13400 g/mol). It was found that the PS chain length and solvent conditions affect the quality of the resulting PS-capped colloidal Au nanoparticles. This work demonstrates, for the first time, a simple, lower-cost approach for templating nonpolar solvent-soluble PS-capped Au nanoparticles on the order of 10-30 nm in diameter. PMID:27357478

  19. Establishment of a sensitive and specific hyper-branched rolling circle amplification assay and test strip for TSV.

    PubMed

    Zhao, Yuran; Yin, Weili; Wang, Ying; Wang, Gongpu; Li, Bafang

    2014-12-01

    A specific padlock probe (PLP) and detection probe were designed to target the capsid protein gene of Taura syndrome virus (TSV), and a hyper-branched rolling circle amplification (HRCA) assay and a corresponding strip-based test were produced. The reaction time and temperature were optimized for both. The PLPs were linked with the target sequence via T4 DNA ligase under conditions of 37°C for 30 min, followed by reaction with Bst DNA polymerase Large Fragment at 61°C for 30 min, and then the test strip was made using the detection probe. Both the assay and the strip had similarly high accuracy and specificity, and their sensitivity was close to 10 copies, which is 100 times higher than that of conventional RT-PCR. We tested 89 batches of shrimps for TSV to assess the HRCA assay and test strip; the results indicated that the TSV HRCA assay and the test strip are rapid diagnostic tools for detection in the field, and have potential for early diagnosis of TSV. PMID:25196450

  20. Fabrication of magnetic water-soluble hyperbranched polyol functionalized graphene oxide for high-efficiency water remediation

    NASA Astrophysics Data System (ADS)

    Hu, Lihua; Li, Yan; Zhang, Xuefei; Wang, Yaoguang; Cui, Limei; Wei, Qin; Ma, Hongmin; Yan, Liangguo; Du, Bin

    2016-06-01

    Magnetic water-soluble hyperbranched polyol functionalized graphene oxide nanocomposite (MWHPO-GO) was successfully prepared and applied to water remediation in this paper. MWHPO-GO was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), magnetization curve, zeta potential, scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses. MWHPO-GO exhibited excellent adsorption performance for the removal of synthetic dyes (methylene blue (MB) and methyl violet (MV)) and heavy metal (Pb(II)). Moreover, MWHPO-GO could be simply recovered from water with magnetic separation. The pseudo-second order equation and the Langmuir model exhibited good correlation with the adsorption kinetic and isotherm data, respectively, for these three pollutants. The thermodynamic results (ΔG < 0, ΔH < 0, ΔS < 0) implied that the adsorption process of MB, MV and Pb(II) was feasible, exothermic and spontaneous in nature. A possible adsorption mechanism has been proposed where π-π stacking interactions, H-bonding interaction and electrostatic attraction dominated the adsorption of MB/MV and chelation and electrostatic attraction dominated the adsorption of Pb(II). In addition, the excellent reproducibility endowed MWHPO-GO with the potential for application in water remediation.

  1. Two-dimensional Hyper-branched Gold Nanoparticles Synthesized on a Two-dimensional Oil/Water Interface

    PubMed Central

    Shin, Yonghee; Lee, Chiwon; Yang, Myung-Seok; Jeong, Sunil; Kim, Dongchul; Kang, Taewook

    2014-01-01

    Two-dimensional (2D) gold nanoparticles can possess novel physical and chemical properties, which will greatly expand the utility of gold nanoparticles in a wide variety of applications ranging from catalysis to biomedicine. However, colloidal synthesis of such particles generally requires sophisticated synthetic techniques to carefully guide anisotropic growth. Here we report that 2D hyper-branched gold nanoparticles in the lateral size range of about 50 ~ 120 nm can be synthesized selectively on a 2D immiscible oil/water interface in a few minutes at room temperature without structure-directing agents. An oleic acid/water interface can provide diffusion-controlled growth conditions, leading to the structural evolution of a smaller gold nucleus to 2D nanodendrimer and nanourchin at the interface. Simulations based on the phase field crystal model match well with experimental observations on the 2D branching of the nucleus, which occurs at the early stage of growth. Branching results in higher surface area and stronger near-field enhancement of 2D gold nanoparticles. This interfacial synthesis can be scaled up by creating an emulsion and the recovery of oleic acid is also achievable by centrifugation. PMID:25156520

  2. Polymer Informatics

    NASA Astrophysics Data System (ADS)

    Adams, Nico

    Polymers are arguably the most important set of materials in common use. The increasing adoption of both combinatorial as well as high-throughput approaches, coupled with an increasing amount of interdisciplinarity, has wrought tremendous change in the field of polymer science. Yet the informatics tools required to support and further enhance these changes are almost completely absent. In the first part of the chapter, a critical analysis of the challenges facing modern polymer informatics is provided. It is argued, that most of the problems facing the field today are rooted in the current scholarly communication process and the way in which chemists and polymer scientists handle and publish data. Furthermore, the chapter reviews existing modes of representing and communicating polymer information and discusses the impact, which the emergence of semantic technologies will have on the way in which scientific and polymer data is published and transmitted. In the second part, a review of the use of informatics tools for the prediction of polymer properties and in silico design of polymers is offered.

  3. Polymers & People

    ERIC Educational Resources Information Center

    Lentz, Linda; Robinson, Thomas; Martin, Elizabeth; Miller, Mary; Ashburn, Norma

    2004-01-01

    Each Tuesday during the fall of 2002, teams of high school students from three South Carolina counties conducted a four-hour polymer institute for their peers. In less than two months, over 300 students visited the Charleston County Public Library in Charleston, South Carolina, to explore DNA, nylon, rubber, gluep, and other polymers. Teams of…

  4. Capabilities for Intercultural Dialogue

    ERIC Educational Resources Information Center

    Crosbie, Veronica

    2014-01-01

    The capabilities approach offers a valuable analytical lens for exploring the challenge and complexity of intercultural dialogue in contemporary settings. The central tenets of the approach, developed by Amartya Sen and Martha Nussbaum, involve a set of humanistic goals including the recognition that development is a process whereby people's…

  5. Project CAPABLE: Model Unit.

    ERIC Educational Resources Information Center

    Madawaska School District, ME.

    Project CAPABLE (Classroom Action Program: Aim: Basic Learning Effectiveness) is a classroom approach which integrates the basic learning skills with content. The goal of the project is to use basic learning skills to enhance the learning of content and at the same time use the content to teach basic learning skills. This manual illustrates how…

  6. Exploration Medical Capability

    NASA Technical Reports Server (NTRS)

    Watkins, Sharmila; Baumann, David; Wu, Jimmy; Barsten, Kristina

    2010-01-01

    Exploration Medical Capability (ExMC) is an element of NASA's Human Research Program (HRP). ExMC's goal is to address the risk of the Inability to Adequately Recognize or Treat an Ill or Injured Crewmember. This poster highlights the approach ExMC has taken to address this goal and our current areas of interest. The Space Medicine Exploration Medical Condition List (SMEMCL) was created to identify medical conditions of concern during exploration missions. The list was derived from space flight medical incidents, the shuttle medical checklist, the International Space Station medical checklist, and expert opinion. The conditions on the list were prioritized according to mission type by a panel comprised of flight surgeons, physician astronauts, engineers, and scientists. From the prioritized list, the ExMC element determined the capabilities needed to address the medical conditions of concern. Where such capabilities were not currently available, a gap was identified. The element s research plan outlines these gaps and the tasks identified to achieve the desired capabilities for exploration missions. This poster is being presented to inform the audience of the gaps and tasks being investigated by ExMC and to encourage discussions of shared interests and possible future collaborations.

  7. Metrology Measurement Capabilities

    SciTech Connect

    Dr. Glen E. Gronniger

    2007-10-02

    This document contains descriptions of Federal Manufacturing & Technologies (FM&T) Metrology capabilities, traceability flow charts, and the measurement uncertainty of each measurement capability. Metrology provides NIST traceable precision measurements or equipment calibration for a wide variety of parameters, ranges, and state-of-the-art uncertainties. Metrology laboratories conform to the requirements of the Department of Energy Development and Production Manual Chapter 13.2, ANSI/ISO/IEC ANSI/ISO/IEC 17025:2005, and ANSI/NCSL Z540-1. FM&T Metrology laboratories are accredited by NVLAP for the parameters, ranges, and uncertainties listed in the specific scope of accreditation under NVLAP Lab code 200108-0. See the Internet at http://ts.nist.gov/Standards/scopes/2001080.pdf. These parameters are summarized. The Honeywell Federal Manufacturing & Technologies (FM&T) Metrology Department has developed measurement technology and calibration capability in four major fields of measurement: (1) Mechanical; (2) Environmental, Gas, Liquid; (3) Electrical (DC, AC, RF/Microwave); and (4) Optical and Radiation. Metrology Engineering provides the expertise to develop measurement capabilities for virtually any type of measurement in the fields listed above. A strong audit function has been developed to provide a means to evaluate the calibration programs of our suppliers and internal calibration organizations. Evaluation includes measurement audits and technical surveys.

  8. Fabrication of sisal fibers/epoxy composites with liquid crystals polymer grafted on sisal fibers

    NASA Astrophysics Data System (ADS)

    Luo, Q. Y.; Lu, S. R.; Song, L. F.; Li, Y. Q.

    2016-07-01

    In this word, microcrystalline cellulose fibers (MCFs), extracted from sisal fibers, were treated with function end-group hyperbranched liquid crystals (HLP). This work brought some insights into the successful surface modification in epoxy composite with HLP. The HLP-MCFs/epoxy composites are studied systematically. The HLP - MCFs/epoxy composites were studied by Fourier transform infrared spectroscopy (FT-IR), polarizing microscope (POM), X-ray photoelectron spectroscopy (XPS) and mechanical properties analysis. The results reveal that the reinforcement of EP composites was carried out by adding HLP-MCFs. In particular, with 1.0 wt% filler loading, the flexural strength, tensile strength, impact strength and flexural modulus of the HLP-MCFs/EP composites were increased by 60%, 69%, 130%, and 192%, respectively. It anticipates that our current work exploits more efficient methods to overcome the few nature fiber/polymer (NPC) adhesion in the interface region and provides implications for the engineering applications of the development of NPC.

  9. Capitalizing on capabilities.

    PubMed

    Ulrich, Dave; Smallwood, Norm

    2004-06-01

    By making the most of organizational capabilities--employees' collective skills and fields of expertise--you can dramatically improve your company's market value. Although there is no magic list of proficiencies that every organization needs in order to succeed, the authors identify 11 intangible assets that well-managed companies tend to have: talent, speed, shared mind-set and coherent brand identity, accountability, collaboration, learning, leadership, customer connectivity, strategic unity, innovation, and efficiency. Such companies typically excel in only three of these capabilities while maintaining industry parity in the other areas. Organizations that fall below the norm in any of the 11 are likely candidates for dysfunction and competitive disadvantage. So you can determine how your company fares in these categories (or others, if the generic list doesn't suit your needs), the authors explain how to conduct a "capabilities audit," describing in particular the experiences and findings of two companies that recently performed such audits. In addition to highlighting which intangible assets are most important given the organization's history and strategy, this exercise will gauge how well your company delivers on its capabilities and will guide you in developing an action plan for improvement. A capabilities audit can work for an entire organization, a business unit, or a region--indeed, for any part of a company that has a strategy to generate financial or customer-related results. It enables executives to assess overall company strengths and weaknesses, senior leaders to define strategy, midlevel managers to execute strategy, and frontline leaders to achieve tactical results. In short, it helps turn intangible assets into concrete strengths. PMID:15202293

  10. Dispersions of Carbon nanotubes in Polymer Matrices

    NASA Technical Reports Server (NTRS)

    Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)

    2010-01-01

    Dispersions of carbon nanotubes exhibiting long term stability are based on a polymer matrix having moieties therein which are capable of a donor-acceptor complexation with carbon nanotubes. The carbon nanotubes are introduced into the polymer matrix and separated therein by standard means. Nanocomposites produced from these dispersions are useful in the fabrication of structures, e.g., lightweight aerospace structures.

  11. Supercontinuum generation and filamentation of ultrashort laser pulses in hybrid silicate nanocomposite materials on the basis of polysaccharides and hyperbranched polyglycidols

    SciTech Connect

    Kul'chin, Yurii N; Golik, S S; Proshenko, D Yu; Chekhlenok, A A; Postnova, I V; Maior, A Yu; Shchipunov, Yurii A

    2013-04-30

    The possibility of using hybrid silicate nanocomposite materials on the basis of polysaccharides and hyperbranched polyglycidols for efficient conversion of pulsed radiation of a femtosecond Ti : sapphire laser at the wavelength 800 nm into supercontinuum in the range from 400 to 1000 nm is experimentally demonstrated. It is established that the addition of a small concentration of Au and CdS nanoparticles to the studied materials essentially affects the efficiency of conversion of the laser radiation energy into the supercontinuum spectrum. (extreme light fields and their applications)

  12. Metrology Measurement Capabilities

    SciTech Connect

    Barnes, L.M.

    2000-03-23

    This document contains descriptions of Federal Manufacturing and Technologies (FM and T) Metrology capabilities, traceability flow charts, and the measurement uncertainty of each measurement capability. Metrology provides NIST traceable precision measurements or equipment calibration for a wide variety of parameters, ranges, and state-of-the-art uncertainties in laboratories that conform to the requirements of the Department of Energy Development and Production Manual Chapter 8.4, and ANSI/NCSL Z540-1 (equivalent to ISO Guide 25). FM and T Metrology laboratories are accredited by NVLAP for the parameters, ranges, and uncertainties listed in the specific scope of accreditation under NVLAP Lab code 200108-0. These parameters are summarized.

  13. Metrology Measurement Capabilities

    SciTech Connect

    Barnes, L.M.

    2003-11-12

    This document contains descriptions of Federal Manufacturing & Technologies (FM&T) Metrology capabilities, traceability flow charts, and the measurement uncertainty of each measurement capability. Metrology provides NIST traceable precision measurements or equipment calibration for a wide variety of parameters, ranges, and state-of-the-art uncertainties. Metrology laboratories conform to the requirements of the Department of Energy Development and Production Manual Chapter 8.4, ANSI/ISO/IEC ANSI/ISO/IEC 17025:2000, and ANSI/NCSL Z540-1 (equivalent to ISO Guide 25). FM&T Metrology laboratories are accredited by NVLAP for the parameters, ranges, and uncertainties listed in the specific scope of accreditation under NVLAP Lab code 200108-0. See the Internet at http://ts.nist.gov/ts/htdocs/210/214/scopes/2001080.pdf. These parameters are summarized in the table at the bottom of this introduction.

  14. Atmospheric Release Advisory Capability

    SciTech Connect

    Dickerson, M.H.; Gudiksen, P.H.; Sullivan, T.J.

    1983-02-01

    The Atmospheric Release Advisory Capability (ARAC) project is a Department of Energy (DOE) sponsored real-time emergency response service available for use by both federal and state agencies in case of a potential or actual atmospheric release of nuclear material. The project, initiated in 1972, is currently evolving from the research and development phase to full operation. Plans are underway to expand the existing capability to continuous operation by 1984 and to establish a National ARAC Center (NARAC) by 1988. This report describes the ARAC system, its utilization during the past two years, and plans for its expansion during the next five to six years. An integral part of this expansion is due to a very important and crucial effort sponsored by the Defense Nuclear Agency to extend the ARAC service to approximately 45 Department of Defense (DOD) sites throughout the continental US over the next three years.

  15. Layered Composite Analysis Capability

    NASA Technical Reports Server (NTRS)

    Narayanaswami, R.; Cole, J. G.

    1985-01-01

    Laminated composite material construction is gaining popularity within industry as an attractive alternative to metallic designs where high strength at reduced weights is of prime consideration. This has necessitated the development of an effective analysis capability for the static, dynamic and buckling analyses of structural components constructed of layered composites. Theoretical and user aspects of layered composite analysis and its incorporation into CSA/NASTRAN are discussed. The availability of stress and strain based failure criteria is described which aids the user in reviewing the voluminous output normally produced in such analyses. Simple strategies to obtain minimum weight designs of composite structures are discussed. Several example problems are presented to demonstrate the accuracy and user convenient features of the capability.

  16. EDITORIAL: Electroactive polymer materials

    NASA Astrophysics Data System (ADS)

    Bar-Cohen, Yoseph; Kim, Kwang J.; Ryeol Choi, Hyouk; Madden, John D. W.

    2007-04-01

    Imitating nature's mechanisms offers enormous potential for the improvement of our lives and the tools we use. This field of the study and imitation of, and inspiration from, nature's methods, designs and processes is known as biomimetics. Artificial muscles, i.e. electroactive polymers (EAPs), are one of the emerging technologies enabling biomimetics. Polymers that can be stimulated to change shape or size have been known for many years. The activation mechanisms of such polymers include electrical, chemical, pneumatic, optical and magnetic. Electrical excitation is one of the most attractive stimulators able to produce elastic deformation in polymers. The convenience and practicality of electrical stimulation and the continual improvement in capabilities make EAP materials some of the most attractive among activatable polymers (Bar-Cohen Y (ed) 2004 Electroactive Polymer (EAP) Actuators as Artificial Muscles—Reality, Potential and Challenges 2nd edn, vol PM136 (Bellingham, WA: SPIE Press) pp 1-765). As polymers, EAP materials offer many appealing characteristics that include low weight, fracture tolerance and pliability. Furthermore, they can be configured into almost any conceivable shape and their properties can be tailored to suit a broad range of requirements. These capabilities and the significant change of shape or size under electrical stimulation while being able to endure many cycles of actuation are inspiring many potential possibilities for EAP materials among engineers and scientists in many different disciplines. Practitioners in biomimetics are particularly excited about these materials since they can be used to mimic the movements of animals and insects. Potentially, mechanisms actuated by EAPs will enable engineers to create devices previously imaginable only in science fiction. For many years EAP materials received relatively little attention due to their poor actuation capability and the small number of available materials. In the last fifteen

  17. Group Capability Model

    NASA Technical Reports Server (NTRS)

    Olejarski, Michael; Appleton, Amy; Deltorchio, Stephen

    2009-01-01

    The Group Capability Model (GCM) is a software tool that allows an organization, from first line management to senior executive, to monitor and track the health (capability) of various groups in performing their contractual obligations. GCM calculates a Group Capability Index (GCI) by comparing actual head counts, certifications, and/or skills within a group. The model can also be used to simulate the effects of employee usage, training, and attrition on the GCI. A universal tool and common method was required due to the high risk of losing skills necessary to complete the Space Shuttle Program and meet the needs of the Constellation Program. During this transition from one space vehicle to another, the uncertainty among the critical skilled workforce is high and attrition has the potential to be unmanageable. GCM allows managers to establish requirements for their group in the form of head counts, certification requirements, or skills requirements. GCM then calculates a Group Capability Index (GCI), where a score of 1 indicates that the group is at the appropriate level; anything less than 1 indicates a potential for improvement. This shows the health of a group, both currently and over time. GCM accepts as input head count, certification needs, critical needs, competency needs, and competency critical needs. In addition, team members are categorized by years of experience, percentage of contribution, ex-members and their skills, availability, function, and in-work requirements. Outputs are several reports, including actual vs. required head count, actual vs. required certificates, CGI change over time (by month), and more. The program stores historical data for summary and historical reporting, which is done via an Excel spreadsheet that is color-coded to show health statistics at a glance. GCM has provided the Shuttle Ground Processing team with a quantifiable, repeatable approach to assessing and managing the skills in their organization. They now have a common

  18. Enhanced Rescue Lift Capability

    NASA Technical Reports Server (NTRS)

    Young, Larry A.

    2007-01-01

    The evolving and ever-increasing demands of emergency response and disaster relief support provided by rotorcraft dictate, among other things, the development of enhanced rescue lift capability for these platforms. This preliminary analysis is first-order in nature but provides considerable insight into some of the challenges inherent in trying to effect rescue using a unique form of robotic rescue device deployed and operated from rotary-wing aerial platforms.

  19. Rippling of polymer nanofibers.

    PubMed

    Wu, Xiang-Fa; Kostogorova-Beller, Yulia Y; Goponenko, Alexander V; Hou, Haoqing; Dzenis, Yuris A

    2008-12-01

    This paper studies the evolution mechanism of surface rippling in polymer nanofibers under axial stretching. This rippling phenomenon has been detected in as-electrospun polyacrylonitrile in recent single-fiber tension tests, and in electrospun polyimide nanofibers after imidization. We herein propose a one-dimensional nonlinear elastic model that takes into account the combined effect of surface tension and nonlinear elasticity during the rippling initiation and its evolution in compliant polymer nanofibers. The polymer nanofiber is modeled as an incompressible, isotropically hyperelastic Mooney-Rivlin solid. The fiber geometry prior to rippling is considered as a long circular cylinder. The governing equation of surface rippling is established through linear perturbation of the static equilibrium state of the nanofiber subjected to finite axial prestretching. The critical stretch and ripple wavelength are determined in terms of surface tension, elastic property, and fiber radius. Numerical examples are demonstrated to examine these dependencies. In addition, a critical fiber radius is determined, below which the polymer nanofibers are intrinsically unstable. The present model, therefore, is capable of predicting the rippling condition in compliant nanofibers, and can be further used as a continuum mechanics approach for the study of surface instability and nonlinear wave propagation in compliant fibers and wires at the nanoscale. PMID:19256861

  20. Organometallic Polymers.

    ERIC Educational Resources Information Center

    Carraher, Charles E., Jr.

    1981-01-01

    Reactions utilized to incorporate a metal-containing moiety into a polymer chain (addition, condensation, and coordination) are considered, emphasizing that these reactions also apply to smaller molecules. (JN)

  1. Polymer flooding

    SciTech Connect

    Littmann, W.

    1988-01-01

    This book covers all aspects of polymer flooding, an enhanced oil recovery method using water soluble polymers to increase the viscosity of flood water, for the displacement of crude oil from porous reservoir rocks. Although this method is becoming increasingly important, there is very little literature available for the engineer wishing to embark on such a project. In the past, polymer flooding was mainly the subject of research. The results of this research are spread over a vast number of single publications, making it difficult for someone who has not kept up-to-date with developments during the last 10-15 years to judge the suitability of polymer flooding to a particular field case. This book tries to fill that gap. An indispensable book for reservoir engineers, production engineers and lab. technicians within the petroleum industry.

  2. Materials Research Capabilities

    NASA Technical Reports Server (NTRS)

    Stofan, Andrew J.

    1986-01-01

    Lewis Research Center, in partnership with U.S. industry and academia, has long been a major force in developing advanced aerospace propulsion and power systems. One key aspect that made many of these systems possible has been the availability of high-performance, reliable, and long-life materials. To assure a continuing flow of new materials and processing concepts, basic understanding to guide such innovation, and technological support for development of major NASA systems, Lewis has supported a strong in-house materials research activity. Our researchers have discovered new alloys, polymers, metallic composites, ceramics, coatings, processing techniques, etc., which are now also in use by U.S. industry. This brochure highlights selected past accomplishments of our materials research and technology staff. It also provides many examples of the facilities available with which we can conduct materials research. The nation is now beginning to consider integrating technology for high-performance supersonic/hypersonic aircraft, nuclear space power systems, a space station, and new research areas such as materials processing in space. As we proceed, I am confident that our materials research staff will continue to provide important contributions which will help our nation maintain a strong technology position in these areas of growing world competition. Lewis Research Center, in partnership with U.S. industry and academia, has long been a major force in developing advanced aerospace propulsion and power systems. One key aspect that made many of these systems possible has been the availability of high-performance, reliable, and long-life materials. To assure a continuing flow of new materials and processing concepts, basic understanding to guide such innovation, and technological support for development of major NASA systems, Lewis has supported a strong in-house materials research activity. Our researchers have discovered new alloys, polymers, metallic composites

  3. Controlled Synthesis of Polymer Brushes via Polymer Single Crystal Templates

    NASA Astrophysics Data System (ADS)

    Zhou, Tian

    A novel synthetic method of polymer brushes using polymer single crystals (PSCs) as solid-state templates is introduced in this study. PSC has a quasi-2D lamellae structure with polymer chains fold back-and-forth perpendicular to the lamellae surfaces. During crystallization, the chain ends are excluded from the unit cell onto the lamellae surfaces, which makes the material extremely versatile in its functionality. Such structure holds the unique capability to harvest nanoparticles, or being immobilized onto macroscopic flat surfaces. After dissolving PSCs in good solvent, polymer brushes are chemically tethered on either nanoparticles or flat macroscopic surfaces. Because the chain-folding structure can be conveniently tailored by changing the molecular weight of polymer and the crystallization temperature, the thickness, grafting density and morphology of resulted polymer brushes can be precisely controlled. As a model system, poly(?-caprolactone) with thiol or alkoxysilane terminal groups was used, and polymer brushes were successfully prepared on both nanoparticles and glass/Au flat surfaces. The structure-property relationships of the as-prepared polymer brushes were studied in detail using multiple characterization techniques. First of all, when functionalizing nanoparticles, by engineering the chain-folding structure of the PSCs, interesting complex nanostructures can be formed by nanoparticles including Janus nanoparticles and nanoparticle dimers. These unique structures render hybrid nanoparticles very interesting responsive behavior which have been studied in detail in this dissertation. When grafted onto a flat surface on the other hand, not only the molecular weight and grafting density can be precisely controlled, the tethering points of a single polymer chain can also be conveniently tailored, resulting polymer brushes with either tail or loop structures. Such difference in brush structure can significantly alter the properties of functional surface

  4. Molecularly imprinted polymers for mycotoxins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molecularly imprinted polymers (MIPs) are a class of synthetic receptors capable of selective recognition of analytes. Recent developments in imprinting technology have made it possible to apply this technology in a range of applications, including mycotoxin detection. Structure-activity relations...

  5. Polymers All Around You!

    ERIC Educational Resources Information Center

    Gertz, Susan

    Background information on natural polymers, synthetic polymers, and the properties of polymers is presented as an introduction to this curriculum guide. Details are provided on the use of polymer products in consumer goods, polymer recycling, polymer densities, the making of a polymer such as GLUEP, polyvinyl alcohol, dissolving plastics, polymers…

  6. Preparation and characterization of multi stimuli-responsive photoluminescent nanocomposites of graphene quantum dots with hyperbranched polyethylenimine derivatives

    NASA Astrophysics Data System (ADS)

    Liu, Xing; Liu, Hua-Ji; Cheng, Fa; Chen, Yu

    2014-06-01

    Oxidized graphene sheets (OGS) were treated with a hyperbranched polyethylenimine (PEI) under hydrothermal conditions to generate nanocomposites of graphene quantum dots (GQDs) functionalized with PEI (GQD-PEIs). The influence of the reaction temperature and the PEI/OGS feed ratio on the photoluminescence properties of the GQD-PEIs was studied. The obtained GQD-PEIs were characterized by TEM, dynamic light scattering, elemental analysis, FTIR, zeta potential measurements and 1H NMR spectroscopy, from which their structural information was inferred. Subsequently, isobutyric amide (IBAm) groups were attached to the GQD-PEIs through the amidation reaction of isobutyric anhydride with the PEI moieties, which resulted in GQD-PEI-IBAm nanocomposites. GQD-PEI-IBAm was not only thermoresponsive, but also responded to other stimuli, including inorganic salts, pH, and loaded organic guests. The cloud point temperature (Tcp) of aqueous solutions of GQD-PEI-IBAm could be modulated through changing the number of IBAm units in GQD-PEI-IBAm, by varying the type and concentration of the inorganic salts and loaded organic guests, or by varying the pH. All the obtained GQD-PEI-IBAm nanocomposites were photoluminescent, and their maximum emission wavelengths were not influenced by outside stimuli. Their emission intensities were influenced a little or negligibly by pH, traditional salting-out anions (Cl- and SO42-), and the relatively polar aspirin guest. However, the traditional salting-in I- anion and the more hydrophobic 1-pyrenebutyric acid (PBA) guest could effectively quench their fluorescence. 2D NOESY 1H NMR spectra verified that GQD-PEI-IBAm accommodated the relatively polar aspirin guest using the PEI-IBAm shell, but adsorbed the relatively hydrophobic PBA guest through the nanographene core. The release rate of the guest encapsulated by the thermoresponsive GQD is different below and above Tcp.Oxidized graphene sheets (OGS) were treated with a hyperbranched

  7. Polymer electronic devices and materials.

    SciTech Connect

    Schubert, William Kent; Baca, Paul Martin; Dirk, Shawn M.; Anderson, G. Ronald; Wheeler, David Roger

    2006-01-01

    Polymer electronic devices and materials have vast potential for future microsystems and could have many advantages over conventional inorganic semiconductor based systems, including ease of manufacturing, cost, weight, flexibility, and the ability to integrate a wide variety of functions on a single platform. Starting materials and substrates are relatively inexpensive and amenable to mass manufacturing methods. This project attempted to plant the seeds for a new core competency in polymer electronics at Sandia National Laboratories. As part of this effort a wide variety of polymer components and devices, ranging from simple resistors to infrared sensitive devices, were fabricated and characterized. Ink jet printing capabilities were established. In addition to promising results on prototype devices the project highlighted the directions where future investments must be made to establish a viable polymer electronics competency.

  8. Remote inhibition of polymer degradation.

    SciTech Connect

    Clough, Roger Lee; Celina, Mathias Christopher

    2005-08-01

    Polymer degradation has been explored on the basis of synergistic infectious and inhibitive interaction between separate materials. A dual stage chemiluminescence detection system with individually controlled hot stages was applied to probe for interaction effects during polymer degradation in an oxidizing environment. Experimental confirmation was obtained that volatile antioxidants can be transferred over a relatively large distance. The thermal degradation of a polypropylene (PP) sample receiving traces of inhibitive antioxidants from a remote source is delayed. Similarly, volatiles from two stabilized elastomers were also capable of retarding a degradation process remotely. This observation demonstrates inhibitive cross-talk as a novel interactive phenomenon between different polymers and is consequential for understanding general polymer interactions, fundamental degradation processes and long-term aging effects of multiple materials in a single environment.

  9. Integrated Analysis Capability Program

    NASA Technical Reports Server (NTRS)

    Vos, R. G.; Beste, D. L.; Greg, J.; Frisch, H. P.

    1991-01-01

    Integrated Analysis Capability (IAC) software system intended to provide highly effective, interactive analysis tool for integrated design of large structures. Supports needs of engineering analysis groups concerned with interdisciplinary problems. Developed to serve as software interface between computer programs from fields of structures, thermodynamics, controls, and dynamics of systems on one hand and executive software system and data base on other hand to yield highly efficient multi-disciplinary system. Special attention given to such users' requirements as handling data and online assistance with operational features and ability to add new modules of user's choice at future date. Written in FORTRAN 77.

  10. IAC - INTEGRATED ANALYSIS CAPABILITY

    NASA Technical Reports Server (NTRS)

    Frisch, H. P.

    1994-01-01

    The objective of the Integrated Analysis Capability (IAC) system is to provide a highly effective, interactive analysis tool for the integrated design of large structures. With the goal of supporting the unique needs of engineering analysis groups concerned with interdisciplinary problems, IAC was developed to interface programs from the fields of structures, thermodynamics, controls, and system dynamics with an executive system and database to yield a highly efficient multi-disciplinary system. Special attention is given to user requirements such as data handling and on-line assistance with operational features, and the ability to add new modules of the user's choice at a future date. IAC contains an executive system, a data base, general utilities, interfaces to various engineering programs, and a framework for building interfaces to other programs. IAC has shown itself to be effective in automatic data transfer among analysis programs. IAC 2.5, designed to be compatible as far as possible with Level 1.5, contains a major upgrade in executive and database management system capabilities, and includes interfaces to enable thermal, structures, optics, and control interaction dynamics analysis. The IAC system architecture is modular in design. 1) The executive module contains an input command processor, an extensive data management system, and driver code to execute the application modules. 2) Technical modules provide standalone computational capability as well as support for various solution paths or coupled analyses. 3) Graphics and model generation interfaces are supplied for building and viewing models. Advanced graphics capabilities are provided within particular analysis modules such as INCA and NASTRAN. 4) Interface modules provide for the required data flow between IAC and other modules. 5) User modules can be arbitrary executable programs or JCL procedures with no pre-defined relationship to IAC. 6) Special purpose modules are included, such as MIMIC (Model

  11. Tissue uptake of docetaxel loaded hydrophobically derivatized hyperbranched polyglycerols and their effects on the morphology of the bladder urothelium.

    PubMed

    Mugabe, Clement; Raven, Peter A; Fazli, Ladan; Baker, Jennifer H E; Jackson, John K; Liggins, Richard T; So, Alan I; Gleave, Martin E; Minchinton, Andrew I; Brooks, Donald E; Burt, Helen M

    2012-01-01

    Recently, we have reported that docetaxel (DTX) loaded, amine terminated hyperbranched polyglycerol (HPG-C(8/10)-MePEG-NH(2)) nanoparticles significantly increased drug uptake in mouse bladder tissues and was the most effective formulation to significantly inhibit tumor growth in an orthotopic model of bladder cancer. The objective of this study was to investigate the effects of HPG-C(8/10)-MePEG-NH(2) nanoparticles on bladder urothelial morphology and integrity, DTX uptake and permeability in bladder tissue and the extent of bladder urothelial recovery following exposure to, and then washout of, HPG-C(8/10)-MePEG-NH(2) nanoparticles. HPG-C(8/10)-MePEG-NH(2) nanoparticles significantly increased the uptake of DTX in both isolated pig bladder as well as in live mouse bladder tissues. Furthermore, HPG-C(8/10)-MePEG-NH(2) nanoparticles were demonstrated to increase the permeability of the urinary bladder wall by causing changes to the urothelial barrier function and morphology through opening of tight junctions and exfoliation of the superficial umbrella cells. These data suggest that exfoliation may be triggered by an apoptosis mechanism, which was followed by a rapid recovery of the urothelium within 24 h post-instillation of HPG-C(8/10)-MePEG-NH(2) nanoparticles. HPG-C(8/10)-MePEG-NH(2) nanoparticles cause significant but rapidly recoverable changes in the bladder urothelial morphology, which we believe may make them suitable for increasing drug permeability of bladder tissue and intravesical drug delivery. PMID:22014457

  12. Multicarboxylic hyperbranched polyglycerol modified SBA-15 for the adsorption of cationic dyes and copper ions from aqueous media

    NASA Astrophysics Data System (ADS)

    Chen, Zhengji; Zhou, Li; Zhang, Faai; Yu, Chuanbai; Wei, Zhibo

    2012-04-01

    The aim of the present work was to investigate the potential of multicarboxylic hyperbranched polyglycerol (HPG) modified mesoporous SBA-15 (SBA/HPG-COOH) as adsorbent for the removal of cationic dyes or/and heavy metal ions from aqueous media. The SBA/HPG-COOH adsorbents can be facilely synthesized through two steps: in situ anionic ring-opening polymerization of glycidol and further modification of hydroxyl groups by succinic anhydride. The resulting SBA/HPG-COOH was characterized by means of FTIR, TGA, XRD, SEM and nitrogen adsorption-desorption isotherms. The results demonstrate that the SBA/HPG-COOH was successfully synthesized and the density of carboxylic groups on the SBA/HPG-COOH is calculated to be as high as 1.5 mmol/g, posing a powerful base for adsorbing cationic adsorbates. Four kinds of dyes and copper ions were chosen as representatives to investigate the adsorption ability of SBA/HPG-COOH. The SBA/HPG-COOH adsorbent showed quick adsorption rate, high adsorption capacity (e.g., its saturated adsorption capacity for methylene blue (MB) can reach 0.50 mmol/g, while for unmodified SBA-15 is lower than 0.05 mmol/g), and high selectivity for cationic adsorbates. The fitness of Langmuir adsorption model and pseudo second-order kinetics on describing the adsorption isotherm and kinetics of SBA/HPG-COOH for MB dye was examined, respectively. It is believed that this robust SBA/HPG-COOH adsorbent will find important application in removal of cationic adsorbates from aqueous solution.

  13. Semiconducting polymers for gas detection

    NASA Technical Reports Server (NTRS)

    Byrd, N. R.; Sheratte, M. B.

    1975-01-01

    Conjugated polyenes, and polyesters containing phthalocyanine in their backbone, were synthesized. These polymers were characterized by chemical analysis, thermogravimetric analysis, spectral analysis, and X-ray diffraction studies for crystallinity, as well as for their film-forming capability and gas/polymer interactions. Most of the polymers were relatively insensitive to water vapor up to 50 percent relative humidity, but the polyester/phthalocyanine (iron) polymer was relatively insensitive up to 100 percent RH. On the other hand, poly(p-dimethylaminophenylacetylene) was too conductive at 100 percent RH. Of the gases tested, the only ones that gave any evidence of interacting with the polymers were SO2, NOx, HCN and NH3. Poly(imidazole)/thiophene responded to each of these gases at all relative humidities, while the other polymers gave varying response, depending upon the RH. Thus, since most of these gases were electron-accepting, the electron-donating character of poly(imidazole)/thiophene substantiates the concept of electronegativity being the operating principle for interaction effects. Of the six polymers prepared, poly(imidazole)/thiophene first showed a very good response to smoldering cotton, but it later became nonresponsive; presumably due to oxidation effects.

  14. Solid polymer membrane program

    NASA Technical Reports Server (NTRS)

    1971-01-01

    The results are presented for a solid polymer electrolyte fuel cell development program. Failure mechanism was identified and resolution of the mechanism experienced in small stack testing was demonstrated. The effect included laboratory analysis and evaluation of a matrix of configurations and operational variables for effects on the degree of hydrogen fluoride released from the cell and on the degree of blistering/delamination occurring in the reactant inlet areas of the cell and to correlate these conditions with cell life capabilities. The laboratory evaluation tests were run at conditions intended to accelerate the degradation of the solid polymer electrolyte in order to obtain relative evaluations as quick as possible. Evaluation of the resolutions for the identified failure mechanism in space shuttle configuration cell assemblies was achieved with the fabrication and life testing of two small stack buildups of four cell assemblies and eight cells each.

  15. Resolving and measuring diffusion in complex interfaces: Exploring new capabilities

    SciTech Connect

    Alam, Todd M.

    2015-09-01

    This exploratory LDRD targeted the use of a new high resolution spectroscopic diffusion capabilities developed at Sandia to resolve transport processes at interfaces in heterogeneous polymer materials. In particular, the combination of high resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy with pulsed field gradient (PFG) diffusion experiments were used to directly explore interface diffusion within heterogeneous polymer composites, including measuring diffusion for individual chemical species in multi-component mixtures. Several different types of heterogeneous polymer systems were studied using these HRMAS NMR diffusion capabilities to probe the resolution limitations, determine the spatial length scales involved, and explore the general applicability to specific heterogeneous systems. The investigations pursued included a) the direct measurement of the diffusion for poly(dimethyl siloxane) polymer (PDMS) on nano-porous materials, b) measurement of penetrant diffusion in additive manufactures (3D printed) processed PDMS composites, and c) the measurement of diffusion in swollen polymers/penetrant mixtures within nano-confined aluminum oxide membranes. The NMR diffusion results obtained were encouraging and allowed for an improved understanding of diffusion and transport processes at the molecular level, while at the same time demonstrating that the spatial heterogeneity that can be resolved using HRMAS NMR PFG diffusion experiment must be larger than ~μm length scales, expect for polymer transport within nanoporous carbons where additional chemical resolution improves the resolvable heterogeneous length scale to hundreds of nm.

  16. Laboratory microfusion capability study

    NASA Astrophysics Data System (ADS)

    1993-05-01

    The purpose of this study is to elucidate the issues involved in developing a Laboratory Microfusion Capability (LMC) which is the major objective of the Inertial Confinement Fusion (ICF) program within the purview of the Department of Energy's Defense Programs. The study was initiated to support a number of DOE management needs: to provide insight for the evolution of the ICF program; to afford guidance to the ICF laboratories in planning their research and development programs; to inform Congress and others of the details and implications of the LMC; to identify criteria for selection of a concept for the Laboratory Microfusion Facility; and to develop a coordinated plan for the realization of an LMC. As originally proposed, the LMC study was divided into two phases. The first phase identifies the purpose and potential utility of the LMC, the regime of its performance parameters, driver independent design issues and requirements, its development goals and requirements, and associated technical, management, staffing, environmental, and other developmental and operational issues. The second phase addresses driver-dependent issues such as specific design, range of performance capabilities, and cost. The study includes four driver options: the neodymium-glass solid state laser, the krypton fluoride excimer gas laser, the light-ion accelerator, and the heavy-ion induction linear accelerator. The results of the Phase 2 study are described in the present report.

  17. Hyperbranched polyglycerol/graphene oxide nanocomposite reinforced hollow fiber solid/liquid phase microextraction for measurement of ibuprofen and naproxen in hair and waste water samples.

    PubMed

    Rezaeifar, Zohreh; Es'haghi, Zarrin; Rounaghi, Gholam Hossein; Chamsaz, Mahmoud

    2016-09-01

    A new design of hyperbranched polyglycerol/graphene oxide nanocomposite reinforced hollow fiber solid/liquid phase microextraction (HBP/GO -HF-SLPME) coupled with high performance liquid chromatography used for extraction and determination of ibuprofen and naproxen in hair and waste water samples. The graphene oxide first synthesized from graphite powders by using modified Hummers approach. The surface of graphene oxide was modified using hyperbranched polyglycerol, through direct polycondensation with thionyl chloride. The ready nanocomposite later wetted by a few microliter of an organic solvent (1-octanol), and then applied to extract the target analytes in direct immersion sampling mode.After the extraction process, the analytes were desorbed with methanol, and then detected via high performance liquid chromatography (HPLC). The experimental setup is very simple and highly affordable. The main factors influencing extraction such as; feed pH, extraction time, aqueous feed volume, agitation speed, the amount of functionalized graphene oxide and the desorption conditions have been examined in detail. Under the optimized experimental conditions, linearity was observed in the range of 5-30,000ngmL(-1) for ibuprofen and 2-10,000ngmL(-1) for naproxen with correlation coefficients of 0.9968 and 0.9925, respectively. The limits of detection were 2.95ngmL(-1) for ibuprofen and 1.51ngmL(-1) for naproxen. The relative standard deviations (RSDs) were found to be less than 5% (n=5). PMID:27428449

  18. Achieving high performance electric field induced strain: a rational design of hyperbranched aromatic polyamide functionalized graphene-polyurethane dielectric elastomer composites.

    PubMed

    Chen, Tian; Qiu, Jinhao; Zhu, Kongjun; Li, Jinhuan; Wang, Jingwen; Li, Shuqin; Wang, Xiaoliang

    2015-03-26

    Dielectric elastomers have great potentials as flexible actuators in micro-electromechanical systems (MEMS) due to their large deformation, light weight, mechanical compliancy, and low cost. The low dielectric constant of these elastomers requires a rather high voltage electric field, which has greatly limited their applications. In this work, a diaphragm-type flexible microactuator comprising a hyperbranched aromatic polyamide functionalized graphene (HAPFG) filler embedded into the polyurethane (PU) dielectric elastomer matrix is described. The rational designed HAPFG sheets exhibits uniform dispersion in PU matrix and strong adhesion with the matrix by hydrogen-bond coupling. Consequently, the HAPFG-PU composites possess high dielectric performance and low loss modulus. The effect of hyperbranched aromatic polyamide functionalized graphene on high voltage electric field induced strain was experimentally investigated using the Fotonic sensor. The high electric field response of the composite was discussed by applying different kinds of alternating-current field. In addition, a comparison of the breakdown strength between the HAPFG-PU composite and the pure PU was carried out. PMID:25741878

  19. PHOBICS physics capabilities

    SciTech Connect

    Baker, M.D.

    1995-12-31

    PHOBOS is the name of a detector and of a research program to study systematically the physics of relativistic heavy-ion collisions over a large range of impact parameters and nuclear species. Collisions with a center of mass energy of 200 A GeV at RHIC are expected to produce the highest energy densities ever accessible in the laboratory. In this writeup, we outline the physics capabilities of the PHOBOS detector and describe the detector design in terms of the general philosophy behind the PHOBOS research program. In order to make the discussion concrete, we then focus on two specific examples of physics measurements that we plan to make at RHIC: dN/d{zeta} for charged particles and the mass spectrum from {phi}{r_arrow} K{sup +}K{sup -} decays.

  20. Nonintrusive subsurface surveying capability

    SciTech Connect

    Tunnell, T.W.; Cave, S.P.

    1994-06-01

    This presentation describes the capabilities of a ground-pentrating radar (GPR) system developed by EG&G Energy Measurements (EM), a prime contractor to the Department of Energy (DOE). The focus of the presentation will be on the subsurface survey of DOE site TA-21 in Los Alamos, New Mexico. EG&G EM developed the system for the Department of Defense. The system is owned by the Department of the Army and currently resides at KO in Albuquerque. EM is pursuing efforts to transfer this technology to environmental applications such as waste-site characterization with DOE encouragement. The Army has already granted permission to use the system for the waste-site characterization activities.

  1. PHOBOS physics capabilities

    SciTech Connect

    Baker, M.D.

    1995-07-15

    PHOBOS is the name of a detector and of a research program to study systematically the physics of relativistic heavy-ion collisions over a large range of impact parameters and nuclear species. Collisions with a center mass energy of 200 A GeV at RHIC are expected to produce the highest energy densities ever accessible in the laboratory. In this writeup, the authors outline the physics capabilities of the PHOBOS detector and describe the detector design in terms of the general philosophy behind the PHOBOS research program. In order to make the discussion concrete, they then focus on two specific examples of physics measurements that they plan to make at RHIC: dN/d{eta} for charged particles and the mass spectrum from {phi} {yields} K{sup +}K{sup {minus}} decays.

  2. General shape optimization capability

    NASA Technical Reports Server (NTRS)

    Chargin, Mladen K.; Raasch, Ingo; Bruns, Rudolf; Deuermeyer, Dawson

    1991-01-01

    A method is described for calculating shape sensitivities, within MSC/NASTRAN, in a simple manner without resort to external programs. The method uses natural design variables to define the shape changes in a given structure. Once the shape sensitivities are obtained, the shape optimization process is carried out in a manner similar to property optimization processes. The capability of this method is illustrated by two examples: the shape optimization of a cantilever beam with holes, loaded by a point load at the free end (with the shape of the holes and the thickness of the beam selected as the design variables), and the shape optimization of a connecting rod subjected to several different loading and boundary conditions.

  3. A method for joining polymers and metals or polymers and ceramics.

    PubMed

    Holtkamp, J; Olowinsky, A

    2009-01-01

    A recently developed laser fusion technique allows polymers to be attached to metals and ceramics in short cycle times. The process and its capabilities are reviewed together with its growing range of applications. PMID:19626949

  4. Capability 9.4 Servicing

    NASA Technical Reports Server (NTRS)

    Moe, Rud

    2005-01-01

    This paper presents viewgraphs on capability structure 9.4 servicing. The topics include: 1) Servicing Description; 2) Benefits of Servicing; 3) Drivers & Assumptions for Servicing; 4) Capability Breakdown Structure 9.4 Servicing; 5) Roadmap for Servicing; 6) 9.4 Servicing Critical Gaps; 7) Capability 9.4 Servicing; 8) Capability 9.4.1 Inspection; 9) State-of-the-Art /Maturity Level /Capabilities for 9.4.1 Inspection; 10) Capability 9.4.2 Diagnostics; 11) State-of-the-Art/Maturity Level /Capabilities for 9.4.2 Diagnostics; 12) Capability 9.4.3 Perform Planned Maintenance; 13) State-of-the-Art /Maturity Level /Capabilities for 9.4.3 Perform Planned Maintenance; 14) Capability 9.4.4 Perform Unplanned Repair; 15) State-of-the-Art /Maturity Level /Capabilities for 9.4.4 Perform Unplanned Repair; 16) Capability 9.4.5 Install Upgrade; 17) Capability 9.4.5 Install Upgrade; 18) State-of-the-Art /Maturity Level /Capabilities for 9.4.5 Install Upgrade; 19) Capability 9.4.6 Planning, Logistics, Training; and 20) State-of-the-Art /Maturity Level /Capabilities for 9.4.6 Planning, Logistics, & Training;

  5. Polymer inflation

    NASA Astrophysics Data System (ADS)

    Hassan, Syed Moeez; Husain, Viqar; Seahra, Sanjeev S.

    2015-03-01

    We consider the semiclassical dynamics of a free massive scalar field in a homogeneous and isotropic cosmological spacetime. The scalar field is quantized using the polymer quantization method assuming that it is described by a Gaussian coherent state. For quadratic potentials, the semiclassical equations of motion yield a universe that has an early "polymer inflation" phase which is generic and almost exactly de Sitter, followed by an epoch of slow-roll inflation. We compute polymer corrections to the slow-roll formalism, and discuss the probability of inflation in this model using a physical Hamiltonian arising from time gauge fixing. We also show how in this model, it is possible to obtain a significant amount of slow-roll inflation from sub-Planckian initial data, hence circumventing some of the criticisms of standard scenarios. These results show the extent to which a quantum gravity motivated quantization method affects early universe dynamics.

  6. Overview of Experimental Capabilities - Supersonics

    NASA Technical Reports Server (NTRS)

    Banks, Daniel W.

    2007-01-01

    This viewgraph presentation gives an overview of experimental capabilities applicable to the area of supersonic research. The contents include: 1) EC Objectives; 2) SUP.11: Elements; 3) NRA; 4) Advanced Flight Simulator Flexible Aircraft Simulation Studies; 5) Advanced Flight Simulator Flying Qualities Guideline Development for Flexible Supersonic Transport Aircraft; 6) Advanced Flight Simulator Rigid/Flex Flight Control; 7) Advanced Flight Simulator Rapid Sim Model Exchange; 8) Flight Test Capabilities Advanced In-Flight Infrared (IR) Thermography; 9) Flight Test Capabilities In-Flight Schlieren; 10) Flight Test Capabilities CLIP Flow Calibration; 11) Flight Test Capabilities PFTF Flowfield Survey; 12) Ground Test Capabilities Laser-Induced Thermal Acoustics (LITA); 13) Ground Test Capabilities Doppler Global Velocimetry (DGV); 14) Ground Test Capabilities Doppler Global Velocimetry (DGV); and 15) Ground Test Capabilities EDL Optical Measurement Capability (PIV) for Rigid/Flexible Decelerator Models.

  7. Advanced CLIPS capabilities

    NASA Technical Reports Server (NTRS)

    Riley, Gary

    1991-01-01

    The C Language Integrated Production System (CLIPS) is a forward chaining rule based language developed by NASA. CLIPS was designed specifically to provide high portability, low cost, and easy integration with external systems. The current release of CLIPS, version 4.3, is being used by over 2500 users throughout the public and private community. The primary addition to the next release of CLIPS, version 5.0, will be the CLIPS Object Oriented Language (COOL). The major capabilities of COOL are: class definition with multiple inheritance and no restrictions on the number, types, or cardinality of slots; message passing which allows procedural code bundled with an object to be executed; and query functions which allow groups of instances to be examined and manipulated. In addition to COOL, numerous other enhancements were added to CLIPS including: generic functions (which allow different pieces of procedural code to be executed depending upon the types or classes of the arguments); integer and double precision data type support; multiple conflict resolution strategies; global variables; logical dependencies; type checking on facts; full ANSI compiler support; and incremental reset for rules.

  8. Enhanced ocean observational capability

    SciTech Connect

    Volpe, A M; Esser, B K

    2000-01-10

    Coastal oceans are vital to world health and sustenance. Technology that enables new observations has always been the driver of discovery in ocean sciences. In this context, we describe the first at sea deployment and operation of an inductively coupled plasma mass spectrometer (ICPMS) for continuous measurement of trace elements in seawater. The purpose of these experiments was to demonstrate that an ICPMS could be operated in a corrosive and high vibration environment with no degradation in performance. Significant advances occurred this past year due to ship time provided by Scripps Institution of Oceanography (UCSD), as well as that funded through this project. Evaluation at sea involved performance testing and characterization of several real-time seawater analysis modes. We show that mass spectrometers can rapidly, precisely and accurately determine ultratrace metal concentrations in seawater, thus allowing high-resolution mapping of large areas of surface seawater. This analytical capability represents a significant advance toward real-time observation and understanding of water mass chemistry in dynamic coastal environments. In addition, a joint LLNL-SIO workshop was convened to define and design new technologies for ocean observation. Finally, collaborative efforts were initiated with atmospheric scientists at LLNL to identify realistic coastal ocean and river simulation models to support real-time analysis and modeling of hazardous material releases in coastal waterways.

  9. Mobile systems capability plan

    SciTech Connect

    1996-09-01

    This plan was prepared to initiate contracting for and deployment of these mobile system services. 102,000 cubic meters of retrievable, contact-handled TRU waste are stored at many sites around the country. Also, an estimated 38,000 cubic meters of TRU waste will be generated in the course of waste inventory workoff and continuing DOE operations. All the defense TRU waste is destined for disposal in WIPP near Carlsbad NM. To ship TRU waste there, sites must first certify that the waste meets WIPP waste acceptance criteria. The waste must be characterized, and if not acceptable, subjected to additional processing, including repackaging. Most sites plan to use existing fixed facilities or open new ones between FY1997-2006 to perform these functions; small-quantity sites lack this capability. An alternative to fixed facilities is the use of mobile systems mounted in trailers or skids, and transported to sites. Mobile systems will be used for all characterization and certification at small sites; large sites can also use them. The Carlsbad Area Office plans to pursue a strategy of privatization of mobile system services, since this offers a number of advantages. To indicate the possible magnitude of the costs of deploying mobile systems, preliminary estimates of equipment, maintenance, and operating costs over a 10-year period were prepared and options for purchase, lease, and privatization through fixed-price contracts considered.

  10. Numerical Study of Thrust Generation in the Process of Laser Ablated Doped Polymer

    NASA Astrophysics Data System (ADS)

    Li, Nanlei; Hong, Yanji; Li, Xiuqian

    2011-11-01

    Recoil impulse of ablation products is a dominant source of thrust during laser ablation of polymers in vacuum. Based on the experiment phenomenon, put forward the threshold energy model to described ablation process, used laser deposition energy in polymer as ablation criterion, and calculated the fluence of energy generation from polymer chemolysis. Take the doped polymer PVC as research object, analyzed and computed interested parameter in process of laser ablated polymer, such as exhaust velocities of ablated product, ablated mass of polymer, recoil momentum gained by polymer target. Consulted experiment data, the numerical model well revealed the propulsion capability of different polymers.

  11. Polymer solutions

    SciTech Connect

    Krawczyk, Gerhard Erich; Miller, Kevin Michael

    2011-07-26

    There is provided a method of making a polymer solution comprising polymerizing one or more monomer in a solvent, wherein said monomer comprises one or more ethylenically unsaturated monomer that is a multi-functional Michael donor, and wherein said solvent comprises 40% or more by weight, based on the weight of said solvent, one or more multi-functional Michael donor.

  12. Polymer Science.

    ERIC Educational Resources Information Center

    Frank, Curtis W.

    1979-01-01

    Described is a series of four graduate level courses in polymer science, offered or currently in preparation, at Stanford University. Course descriptions and a list of required and recommended texts are included. Detailed course outlines for two of the courses are presented. (BT)

  13. Functional polymers

    SciTech Connect

    Wegner, G.

    2000-01-01

    Improving the existing polymer materials and the designing of model polymers need fundamental insights into the structure and dynamics over a large range of length and time scales. Consequently, a host of quite different methods needs to be applied to gain insights into the molecular and supramolecular structures and interactions that determine the performance of these materials. Supramolecular structures derived from shape persistent (stiff) macromolecules are used as examples to demonstrate the correlation between chemical structure, order phenomena and performance in applications concerning advanced or developing technologies: organic light emitting diodes (OLEDs) and separator membranes in lithium based batteries and fuel cells. Polymers are also important as additives in the manufacture and the processing of other materials. The design of block copolymers to control the nucleation and growth of inorganic particles precipitating from aqueous solutions (mineralization) is discussed as well as the use of block copolymers to optimize the processing of ceramic pieces and objects. Finally, the modification of surfaces by polymers including aspects of biocompatibility is discussed. Some remarks concerning the importance of recent developments and advances in synthesis of macromolecular materials are also given.

  14. Advances in the biomedical application of polymer-functionalized carbon nanotubes.

    PubMed

    Soleyman, Rouhollah; Hirbod, Sorina; Adeli, Mohsen

    2015-05-01

    Nowadays, carbon nanotubes (CNTs) have attracted the attention of scientists because of their unique electronic, magnetic, optical, mechanical, and chemical properties. However, their poor solubility in solvents, especially in water, limits their applications in several promising fields such as biomedicine, biomedical imaging, and cancer therapy. The attachment of hydrophilic segments to CNTs is a very efficient method for overcoming this problem. This review covers the latest advances in the synthesis of water-soluble CNTs with an emphasis on the molecular structure of various categories of hydrophilic molecules/macromolecules which have been grafted onto the surface of CNTs. Indeed, from the viewpoint of chemical synthesis, covalent bonding of several water-soluble molecules/macromolecules including small water-soluble organic molecules, linear, hyperbranched and dendritic polymers/biopolymers, glycoconjugate molecules/polymers as well as biomolecules onto the surface of CNTs has been deeply surveyed. Moreover, the most recent and interesting bio-applications of polymer-functionalized water-soluble CNTs have been properly reviewed. PMID:26222588

  15. Efficient delivery of NF-κB siRNA to human retinal pigment epithelial cells with hyperbranched cationic polysaccharide derivative-based nanoparticles

    PubMed Central

    Liu, Zhenzhen; Gong, Haijun; Zeng, Rui; Liang, Xuan; Zhang, Li-Ming; Yang, Liqun; Lan, Yuqing

    2015-01-01

    A hyperbranched cationic polysaccharide derivative-mediated small interfering (si)RNA interference strategy was proposed to inhibit nuclear transcription factor-kappa B (NF-κB) activation in human retinal pigment epithelial (hRPE) cells for the gene therapy of diabetic retinopathy. Two hyperbranched cationic polysaccharide derivatives containing the same amount of cationic residues, but with different branching structures and molecular weights, including 3-(dimethylamino)-1-propylamine-conjugated glycogen (DMAPA-Glyp) and amylopectin (DMAPA-Amp) derivatives, were developed for the efficient delivery of NF-κB siRNA into hRPE cells. The DMAPA-Glyp derivative showed lower toxicity against hRPE cells. Furthermore, the DMAPA-Glyp derivative more readily condensed siRNA and then formed the nanoparticles attributed to its higher branching architecture when compared to the DMAPA-Amp derivative. Both DMAPA-Glyp/siRNA and DMAPA-Amp/siRNA nanoparticles were able to protect siRNA from degradation by nuclease in 25% fetal bovine serum. The particle sizes of the DMAPA-Glyp/siRNA nanoparticles (70–120 nm) were smaller than those of the DMAPA-Amp/siRNA nanoparticles (130–180 nm) due to the higher branching architecture and lower molecular weight of the DMAPA-Glyp derivative. In addition, the zeta potentials of the DMAPA-Glyp/siRNA nanoparticles were higher than those of the DMAPA-Glyp/siRNA nanoparticles. As a result, siRNA was much more efficiently transferred into hRPE cells using the DMAPA-Glyp/siRNA nanoparticles rather than the DMAPA-Amp/siRNA nanoparticles. This led to significantly high levels of suppression on the expression levels of NF-κB p65 messenger RNA and protein in the cells transfected with DMAPA-Glyp/siRNA nanoparticles. This work provides a potential approach to promote hyperbranched polysaccharide derivatives as nonviral siRNA vectors for the inhibition of NF-κB activation in hRPE cells. PMID:25897219

  16. Small rover exploration capabilities

    NASA Astrophysics Data System (ADS)

    Salotti, Jean-Marc; Laithier, Corentin; Machut, Benoit; Marie, Aurélien; Bruneau, Audrey; Grömer, Gernot; Foing, Bernard H.

    2015-05-01

    For a human mission to the Moon or Mars, an important question is to determine the best strategy for the choice of surface vehicles. Recent studies suggest that the first missions to Mars will be strongly constrained and that only small unpressurized vehicles will be available. We analyze the exploration capabilities and limitations of small surface vehicles from the user perspective. Following the “human centered design” paradigm, the team focused on human systems interactions and conducted the following experiments: - Another member of our team participated in the ILEWG EuroMoonMars 2013 simulation at the Mars Desert Research Station in Utah during the same period of time. Although the possible traverses were restricted, a similar study with analog space suits and quads has been carried out. - Other experiments have been conducted in an old rock quarry close to Bordeaux, France. An expert in the use of quads for all types of terrains performed a demonstration and helped us to characterize the difficulties, the risks and advantages and drawbacks of different vehicles and tools. The vehicles that will be used on the surface of Mars have not been defined yet. Nevertheless, the results of our project already show that using a light and unpressurized vehicle (in the order of 150 kg) for the mobility on the Martian surface can be a true advantage. Part of the study was dedicated to the search for appropriate tools that could be used to make

  17. Optical and mechanical design advantages using polymer optics

    NASA Astrophysics Data System (ADS)

    Doushkina, Valentina; Fleming, Erik

    2009-08-01

    Precision diamond-turned or molded polymer optics are utilized in a wide range of commercial markets and applications including; medical disposables, bar code scan/recognition, security and fingerprint scanners, motion and presence sensors, CCD cameras, laser collimation and others.. The use of polymer optics was previously relegated to less technically challenging applications. Current advancements in polymer technology and injection molding capabilities have increased the manufacturability and precision of polymer optics. Polymer materials with optical properties are being thrust to the design forefront for new, sophisticated electro-optical applications. Designing and manufacturing optics and optical systems using polymers alone or hybrid polymer/glass applications provides complete custom capability and offers new optical and opto-mechanical solutions for a variety of optical and opto-mechanical modules, assemblies and components. Integrated mounting offers configuration flexibility, considerable design freedom, simplified optical alignment, mechanical design, assembly and packaging. The system is assembled, aligned, optically spaced, and sealed in a single manufacturing step.

  18. LANL Analytical and Radiochemistry Capabilities

    SciTech Connect

    Steiner, Robert E.; Burns, Carol J.; Lamont, Stephen P.; Tandon, Lav

    2012-07-27

    The overview of this presentation is: (1) Introduction to nonproliferation efforts; (2) Scope of activities Los Alamos National Laboratory; (3) Facilities for radioanalytical work at LANL; (4) Radiochemical characterization capabilities; and (5) Bulk chemical and materials analysis capabilities.

  19. Selenium-Substituted Hydroxyapatite/Biodegradable Polymer/Pamidronate Combined Scaffold for the Therapy of Bone Tumour

    PubMed Central

    Oledzka, Ewa; Sobczak, Marcin; Kolmas, Joanna; Nalecz-Jawecki, Grzegorz

    2015-01-01

    The present study evaluated a new concept of combined scaffolds as a promising bone replacement material for patients with a bone tumour or bone metastasis. The scaffolds were composed of hydroxyapatite doped with selenium ions and a biodegradable polymer (linear or branched), and contained an active substance—bisphosphonate. For this purpose, a series of biodegradable polyesters were synthesized through a ring-opening polymerization of ε-caprolactone or d,l-lactide in the presence of 2-hydroxyethyl methacrylate (HEMA) or hyperbranched 2,2-bis(hydroxymethyl)propionic acid polyester-16-hydroxyl (bis-MPA) initiators, substances often used in the synthesis of medical materials. The polymers were obtained with a high yield and a number-average molecular weight up to 45,300 (g/mol). The combined scaffolds were then manufactured by a direct compression of pre-synthesized hydroxyapatite doped with selenite or selenate ions, obtained polymer and pamidronate as a model drug. It was found that the kinetic release of the drug from the scaffolds tested in vitro under physiological conditions is strongly dependent on the physicochemical properties and average molecular weight of the polymers. Furthermore, there was good correlation with the hydrolytic biodegradation results of the scaffolds fabricated without drug. The preliminary findings suggest that the fabricated combined scaffolds could be effectively used for the sustained delivery of bioactive molecules at bone defect sites. PMID:26389884

  20. Selenium-Substituted Hydroxyapatite/Biodegradable Polymer/Pamidronate Combined Scaffold for the Therapy of Bone Tumour.

    PubMed

    Oledzka, Ewa; Sobczak, Marcin; Kolmas, Joanna; Nalecz-Jawecki, Grzegorz

    2015-01-01

    The present study evaluated a new concept of combined scaffolds as a promising bone replacement material for patients with a bone tumour or bone metastasis. The scaffolds were composed of hydroxyapatite doped with selenium ions and a biodegradable polymer (linear or branched), and contained an active substance-bisphosphonate. For this purpose, a series of biodegradable polyesters were synthesized through a ring-opening polymerization of ε-caprolactone or d,l-lactide in the presence of 2-hydroxyethyl methacrylate (HEMA) or hyperbranched 2,2-bis(hydroxymethyl)propionic acid polyester-16-hydroxyl (bis-MPA) initiators, substances often used in the synthesis of medical materials. The polymers were obtained with a high yield and a number-average molecular weight up to 45,300 (g/mol). The combined scaffolds were then manufactured by a direct compression of pre-synthesized hydroxyapatite doped with selenite or selenate ions, obtained polymer and pamidronate as a model drug. It was found that the kinetic release of the drug from the scaffolds tested in vitro under physiological conditions is strongly dependent on the physicochemical properties and average molecular weight of the polymers. Furthermore, there was good correlation with the hydrolytic biodegradation results of the scaffolds fabricated without drug. The preliminary findings suggest that the fabricated combined scaffolds could be effectively used for the sustained delivery of bioactive molecules at bone defect sites. PMID:26389884

  1. Facile preparation of highly luminescent CdTe quantum dots within hyperbranched poly(amidoamine)s and their application in bio-imaging

    PubMed Central

    2014-01-01

    A new strategy for facile preparation of highly luminescent CdTe quantum dots (QDs) within amine-terminated hyperbranched poly(amidoamine)s (HPAMAM) was proposed in this paper. CdTe precursors were first prepared by adding NaHTe to aqueous Cd2+ chelated by 3-mercaptopropionic sodium (MPA-Na), and then HPAMAM was introduced to stabilize the CdTe precursors. After microwave irradiation, highly fluorescent and stable CdTe QDs stabilized by MPA-Na and HPAMAM were obtained. The CdTe QDs showed a high quantum yield (QY) up to 58%. By preparing CdTe QDs within HPAMAM, the biocompatibility properties of HPAMAM and the optical, electrical properties of CdTe QDs can be combined, endowing the CdTe QDs with biocompatibility. The resulting CdTe QDs can be directly used in biomedical fields, and their potential application in bio-imaging was investigated. PMID:24624925

  2. Polymer-composite ball lightning.

    PubMed

    Bychkov, V L

    2002-01-15

    Investigations into the state of ball lightning (BL) have been made, and both theory and experiments, related to so-called "polymer-composite" ball lightning, are presented. The properties of such a polymeric BL have been described and are that of a long-lived object capable of storing high energy. Results of experiments, starting with polymeric components in erosive gas discharge experiments, are described and discussed. The model of BL as a highly charged polymer-dielectric structure is described. According to this model BL appears as the result of the aggregation of natural polymers, such as lignin and cellulose, soot, polymeric silica and other natural dust particles. Its ability to glow is explained by the appearance over its perimeter of gas discharges near the highly charged BL surface, and electrical breakdown of some regions on the surface, consisting of polymerized and aggregated threads. PMID:16210170

  3. Advanced Polymer

    NASA Technical Reports Server (NTRS)

    1992-01-01

    In the mid-1980's, Langley developed a polyimide sulfone, combining desirable properties of two classes of polymers. Composites and other products made from polyimide sulfone can be used with solvents and corrosive fluids, are light weight, low cost and can be easily fabricated for a wide range of industrial uses. High Technology Systems, Inc. obtained a license for the polymer and was awarded a Small Business Innovation Research (SBIR) contract for development in a powder form. Although its principal use is as a matrix resin for composites, the material can also be used as a high temperature structural adhesive for aircraft structures and as a coating for protection from heat and radiation for electronic components.

  4. Phthalocyanine polymers

    NASA Technical Reports Server (NTRS)

    Achar, B. N.; Fohlen, G. M.; Parker, J. A. (Inventor)

    1985-01-01

    A method of forming 4,4',4'',4''' -tetraamino phthalocyanines involves reducing 4,4',4'',4''' -tetranitro phthalocyanines, polymerizing the metal tetraamino phthalocyanines with a tetracarboxylic dianhydride (preferably aromatic) or copolymerizing with a tetracarboxylic dianhydride and a diamine (preferably also aromatic) to produce amic acids which are then dehydrocyclized to imides. Thermally and oxidatively stable polymers result which form tough, flexible films, varnishes, adhesives, and fibers.

  5. Periodic Polymers

    NASA Astrophysics Data System (ADS)

    Thomas, Edwin

    2013-03-01

    Periodic polymers can be made by self assembly, directed self assembly and by photolithography. Such materials provide a versatile platform for 1, 2 and 3D periodic nano-micro scale composites with either dielectric or impedance contrast or both, and these can serve for example, as photonic and or phononic crystals for electromagnetic and elastic waves as well as mechanical frames/trusses. Compared to electromagnetic waves, elastic waves are both less complex (longitudinal modes in fluids) and more complex (longitudinal, transverse in-plane and transverse out-of-plane modes in solids). Engineering of the dispersion relation between wave frequency w and wave vector, k enables the opening of band gaps in the density of modes and detailed shaping of w(k). Band gaps can be opened by Bragg scattering, anti-crossing of bands and discrete shape resonances. Current interest is in our group focuses using design - modeling, fabrication and measurement of polymer-based periodic materials for applications as tunable optics and control of phonon flow. Several examples will be described including the design of structures for multispectral band gaps for elastic waves to alter the phonon density of states, the creation of block polymer and bicontinuous metal-carbon nanoframes for structures that are robust against ballistic projectiles and quasi-crystalline solid/fluid structures that can steer shock waves.

  6. Solid state structure and gas transport behavior of semicrystalline poly(ethylene terephthalate) and barrier coatings based on polyhydroxylated dendritic polymers

    NASA Astrophysics Data System (ADS)

    Lin, Jun

    The existence of rigid amorphous fraction (RAF) in semicrystalline poly(ethylene terephthalate) (PET) is associated with the lamellar stack crystalline morphology of this polymer, the regions where several crystalline lamellas are separated by very thin (20--40A) amorphous layers. In contrast, regular or mobile amorphous fraction (MAF) is associated with much thicker interstack regions. The specific volume of RAF in cold and melt crystallized PET was probed at 25°C using oxygen solubility measurements, and showed a direct correlation with the crystallization temperature. It was shown that upon crystallization from either melt or glassy state, RAF vitrifies at the crystallization temperature and resembles the glassy behavior despite high temperature. When cooled to room temperature, the RAF preserves a memory about the melt state of polymer, which is uniquely defined by the crystallization temperature. Consistent results were demonstrated by positron annihilation lifetime spectroscopy (PALS) study. Moreover, correlations between PALS and oxygen transport parameters suggested that the dominant free volume parameter which controls the diffusion process is the hole volume, whereas the dominant parameter controlling the solubility is the hole density. Oxygen transport properties were assessed for a series of hydroxyl-functional hyperbranched polyesters (HBPs) at both 0% and 50% relative humidity (RH). At 0% RH, all HBPs showed outstanding oxygen barrier properties, with the permeability coefficients more than one order magnitude smaller than that of the amorphous PET. It was found that the oxygen diffusion process was mainly determined by the free volume and characteristic jump length of gas molecules from one core to another core. On the other hand, the oxygen sorption was related with the glass transition temperature, following dual-sorption model. The different amount of volume fraction of periphery layers contributed to the difference in oxygen solubility among

  7. Influence of polymer network in polymer-stabilized ferroelectric liquid crystals and its direct observation using a confocal microscope

    NASA Astrophysics Data System (ADS)

    Petkovšek, R.; Pirš, J.; Kralj, S.; Čopič, M.; Šuput, D.

    2006-01-01

    The paper presents the analysis of the three-dimensional polymer network distribution inside the polymer-stabilized ferroelectric liquid-crystal layer based on the laser scanning fluorescence confocal microscopy and a fluorescent dye tagging of the polymer. The studies of polymer-stabilized ferroelectric liquid-crystal structures described in this paper are focused on the comparison of the influence of polymer network in case that the polymerization is initiated in the chevron as well as in the quasibookshelf liquid-crystal molecular orientation. In the case of the chevron structure the regular distribution of the polymer network within the layer leads to the monostability of the chevron state. On the other hand the specific distribution of the polymer in the polymer-stabilized quasibookshelf stripe textures leads to the perfect bistability, improved multiplex driving, and analog gray scale capability.

  8. Polymer Electronics: Power from Polymers

    SciTech Connect

    Venkataraman, D.; Russell, Thomas P.

    2012-06-19

    We review polymer-based electronics and photovoltaics to provide the reader with a sense of how the field has developed, where we stand at present, and what possibilities are looming in the future. Expertise in areas ranging from synthesis to morphology to device design was sought to achieve this end. While these reviews cannot be exhaustive, they do provide a snapshot of the field at present and give some sense of where the key impediments are.

  9. Polymers influencing transportability profile of drug.

    PubMed

    Gaikwad, Vinod L; Bhatia, Manish S

    2013-10-01

    Drug release from various polymers is generally governed by the type of polymer/s incorporated in the formulation and mechanism of drug release from polymer/s. A single polymer may show one or more mechanisms of drug release out of which one mechanism is majorly followed for drug release. Some of the common mechanisms of drug release from polymers were, diffusion, swelling, matrix release, leaching of drug, etc. Mechanism or rate of drug release from a polymer or a combination of polymers can be predicted by using different computational methods or models. These models were capable of predicting drug release from its dosage form in advance without actual formulation and testing of drug release from dosage form. Quantitative structure-property relationship (QSPR) is an important tool used in the prediction of various physicochemical properties of actives as well as inactives. Since last several decades QSPR has been applied in new drug development for reducing the total number of drugs to be synthesized, as it involves a selection of the most desirable compound of interest. This technique was also applied in predicting in vivo performance of drug/s for various parameters. QSPR serves as a predictive tool to correlate structural descriptors of molecules with biological as well as physicochemical properties. Several researchers have contributed at different extents in this area to modify various properties of pharmaceuticals. The present review is focused on a study of different polymers that influence the transportability profiles of drugs along with the application of QSPR either to study different properties of polymers that regulate drug release or in predicting drug transportability from different polymer systems used in formulations. PMID:24227951

  10. On Building Inexpensive Network Capabilities

    SciTech Connect

    Shue, Craig A; Kalafut, Prof. Andrew; Allman, Mark; Taylor, Curtis R

    2011-01-01

    There are many deployed approaches for blocking unwanted traffic, either once it reaches the recipient's network, or closer to its point of origin. One of these schemes is based on the notion of traffic carrying capabilities that grant access to a network and/or end host. However, leveraging capabilities results in added complexity and additional steps in the communication process: Before communication starts a remote host must be vetted and given a capability to use in the subsequent communication. In this paper, we propose a lightweight mechanism that turns the answers provided by DNS name resolution---which Internet communication broadly depends on anyway---into capabilities. While not achieving an ideal capability system, we show the mechanism can be built from commodity technology and is therefore a pragmatic way to gain some of the key benefits of capabilities without requiring new infrastructure.

  11. Integrated Analysis Capability (IAC) development

    NASA Technical Reports Server (NTRS)

    Young, J. P.

    1981-01-01

    The technical and programmatic aspects of the integrated analysis capability (IAC) are described. The (IAC) is an interdisciplinary analysis system containing a wide range of general purpose analysis programs that are interfaced via a common data base and a unified executive. The system is designed with significant interactive capability as well as the capability to support the entire range of design phases from the definition phase to the verification phase. The system functions as a standalone or interfaced with IPAD.

  12. Indigenous Research Capability in Aotearoa

    ERIC Educational Resources Information Center

    Ormond, Adreanne; Williams, Les R. Tumoana

    2013-01-01

    This article begins by considering the general nature of capability, from some dictionary meanings, then extends to theoretical perspectives related to the capability approach. As a consequence, we arrive at an operational definition that emphasises the ability to solve problems in a systematic way that brings transformation. In these terms,…

  13. Identifying 21st Century Capabilities

    ERIC Educational Resources Information Center

    Stevens, Robert

    2012-01-01

    What are the capabilities necessary to meet 21st century challenges? Much of the literature on 21st century skills focuses on skills necessary to meet those challenges associated with future work in a globalised world. The result is a limited characterisation of those capabilities necessary to address 21st century social, health and particularly…

  14. Interpretations of Polymer-Polymer Miscibility.

    ERIC Educational Resources Information Center

    Olabisi, Olagoke

    1981-01-01

    Discusses various aspects of polymeric mixtures, mixtures of structurally different homopolymers, copolymers, terpolymers, and the like. Defines concepts of polymer-polymer miscibility from practical and theoretical viewpoints, and ways of predicting such miscibility. (JN)

  15. NASA Capability Roadmaps Executive Summary

    NASA Technical Reports Server (NTRS)

    Willcoxon, Rita; Thronson, Harley; Varsi, Guilio; Mueller, Robert; Regenie, Victoria; Inman, Tom; Crooke, Julie; Coulter, Dan

    2005-01-01

    This document is the result of eight months of hard work and dedication from NASA, industry, other government agencies, and academic experts from across the nation. It provides a summary of the capabilities necessary to execute the Vision for Space Exploration and the key architecture decisions that drive the direction for those capabilities. This report is being provided to the Exploration Systems Architecture Study (ESAS) team for consideration in development of an architecture approach and investment strategy to support NASA future mission, programs and budget requests. In addition, it will be an excellent reference for NASA's strategic planning. A more detailed set of roadmaps at the technology and sub-capability levels are available on CD. These detailed products include key driving assumptions, capability maturation assessments, and technology and capability development roadmaps.

  16. Electrostatically stricted polymers (ESSP)

    NASA Astrophysics Data System (ADS)

    Liu, Chang; Bar-Cohen, Yoseph; Leary, Sean P.

    1999-05-01

    Miniature, lightweight, miser actuators that operate similar to biological muscles can be used to develop robotic devices with unmatched capabilities and impact many technology areas. Electroactive polymers (EAP) offer the potential to producing such actuators and their main attractive feature is their ability to induce relatively large bending or longitudinal strain. Generally, these materials produce a relatively low force and the applications that can be considered at the current state of the art are relatively limited. While improved material are being developed there is a need for methods to develop longitudinal actuators that can contract similar to muscles. In addition, it is desirable to have these actuators in a fiber form that can be bundled to provide the necessary characteristics of stiffness, fracture toughness, resilience and large force actuation. To address this need efforts were made to develop both the material basis as well as the electromechanical modeling of the actuator.

  17. Molecularly imprinted polymers for biomedical and biotechnological applications

    NASA Astrophysics Data System (ADS)

    Dmitrienko, E. V.; Pyshnaya, I. A.; Martyanov, O. N.; Pyshnyi, D. V.

    2016-05-01

    This survey covers main advances in the preparation and application of molecularly imprinted polymers which are capable of specific recognition of biologically active compounds. The principles underlying the production of highly efficient and template-specific molecularly imprinted polymers are discussed. The focus is on the imprinting of highly structured macromolecular and supramolecular templates. The existing and potential applications of molecularly imprinted polymers in various fields of chemistry and molecular biology are considered. The bibliography includes 261 references.

  18. Pairwise polymer blends for oral drug delivery.

    PubMed

    Marks, Joyann A; Wegiel, Lindsay A; Taylor, Lynne S; Edgar, Kevin J

    2014-09-01

    Blends of polymers with complementary properties hold promise for addressing the diverse, demanding polymer performance requirements in amorphous solid dispersions (ASDs), but we lack comprehensive property understanding for blends of important ASD polymers. Herein, we prepare pairwise blends of commercially available polymers polyvinylpyrrolidone (PVP), the cationic acrylate copolymer Eudragit 100 (E100), hydroxypropyl methylcellulose acetate succinate (HPMCAS), carboxymethyl cellulose acetate butyrate (CMCAB), hydroxypropyl methylcellulose (HPMC), and the new derivative cellulose acetate adipate propionate (CAAdP). This study identifies miscible binary blends that may find use, for example, in ASDs for solubility and bioavailability enhancement of poorly water-soluble drugs. Differential scanning calorimetry, FTIR spectroscopy, and film clarity were used to determine blend miscibility. Several polymer combinations including HPMCAS/PVP, HPMC/CMCAB, and PVP/HPMC appear to be miscible in all proportions. In contrast, blends of E100/PVP and E100/HPMC showed a miscibility gap. Combinations of water-soluble and hydrophobic polymers like these may permit effective balancing of ASD performance criteria such as release rate and polymer-drug interaction to prevent nucleation and crystal growth of poorly soluble drugs. Miscible polymer combinations described herein will enable further study of their drug delivery capabilities, and provide a potentially valuable set of ASD formulation tools. PMID:24823790

  19. Ionic-Liquid-Based Polymer Electrolytes for Battery Applications.

    PubMed

    Osada, Irene; de Vries, Henrik; Scrosati, Bruno; Passerini, Stefano

    2016-01-11

    The advent of solid-state polymer electrolytes for application in lithium batteries took place more than four decades ago when the ability of polyethylene oxide (PEO) to dissolve suitable lithium salts was demonstrated. Since then, many modifications of this basic system have been proposed and tested, involving the addition of conventional, carbonate-based electrolytes, low molecular weight polymers, ceramic fillers, and others. This Review focuses on ternary polymer electrolytes, that is, ion-conducting systems consisting of a polymer incorporating two salts, one bearing the lithium cation and the other introducing additional anions capable of plasticizing the polymer chains. Assessing the state of the research field of solid-state, ternary polymer electrolytes, while giving background on the whole field of polymer electrolytes, this Review is expected to stimulate new thoughts and ideas on the challenges and opportunities of lithium-metal batteries. PMID:26783056

  20. Initiation of polymer degradation via transfer of infectious species.

    SciTech Connect

    Clough, Roger Lee; Jones, Gary Dunn; Celina, Mathias Christopher

    2005-06-01

    A novel dual stage chemiluminescence detection system incorporating individually controlled hot stages has been developed and applied to probe for material interaction effects during polymer degradation. Utilization of this system has resulted in experimental confirmation for the first time that in an oxidizing environment a degrading polymer A (in this case polypropylene, PP) is capable of infecting a different polymer B (in this case polybutadiene, HTPB) over a relatively large distance. In the presence of the infectious degrading polymer A, the thermal degradation of polymer B is observed over a significantly shorter time period. Consistent with infectious volatiles from material A initiating the degradation process in material B it was demonstrated that traces (micrograms) of a thermally sensitive peroxide in the vicinity of PP could induce degradation remotely. This observation documents cross-infectious phenomena between different polymers and has major consequences for polymer interactions, understanding fundamental degradation processes and long-term aging effects under combined material exposures.

  1. Initiation of polymer degradation via transfer of infectious species.

    SciTech Connect

    Clough, Roger Lee; Jones, Gary D.; Celina, Mathias Christopher

    2005-02-01

    A novel dual stage chemiluminescence detection system incorporating individually controlled hot stages has been developed and applied to probe for material interaction effects during polymer degradation. Utilization of this system has resulted in experimental confirmation for the first time that in an oxidizing environment a degrading polymer A (in this case polypropylene, PP) is capable of infecting a different polymer B (in this case polybutadiene, HTPB) over a relatively large distance. In the presence of the infectious degrading polymer A, the thermal degradation of polymer B is observed over a significantly shorter time period. Consistent with infectious volatiles from material A initiating the degradation process in material B it was demonstrated that traces (micrograms) of a thermally sensitive peroxide in the vicinity of PP could induce degradation remotely. This observation documents cross-infectious phenomena between different polymers and has major consequences for polymer interactions, understanding fundamental degradation processes and long-term aging effects under combined material exposures.

  2. From Commodity Polymers to Functional Polymers

    PubMed Central

    Xiang, Tao; Wang, Ling-Ren; Ma, Lang; Han, Zhi-Yuan; Wang, Rui; Cheng, Chong; Xia, Yi; Qin, Hui; Zhao, Chang-Sheng

    2014-01-01

    Functional polymers bear specified chemical groups, and have specified physical, chemical, biological, pharmacological, or other uses. To adjust the properties while keeping material usage low, a method for direct synthesis of functional polymers is indispensable. Here we show that various functional polymers can be synthesized by in situ cross-linked polymerization/copolymerization. We demonstrate that the polymers synthesized by the facile method using different functional monomers own outstanding pH-sensitivity and pH-reversibility, antifouling property, antibacterial, and anticoagulant property. Our study opens a route for the functionalization of commodity polymers, which lead to important advances in polymeric materials applications. PMID:24710333

  3. MCNP: Multigroup/adjoint capabilities

    SciTech Connect

    Wagner, J.C.; Redmond, E.L. II; Palmtag, S.P.; Hendricks, J.S.

    1994-04-01

    This report discusses various aspects related to the use and validity of the general purpose Monte Carlo code MCNP for multigroup/adjoint calculations. The increased desire to perform comparisons between Monte Carlo and deterministic codes, along with the ever-present desire to increase the efficiency of large MCNP calculations has produced a greater user demand for the multigroup/adjoint capabilities. To more fully utilize these capabilities, we review the applications of the Monte Carlo multigroup/adjoint method, describe how to generate multigroup cross sections for MCNP with the auxiliary CRSRD code, describe how to use the multigroup/adjoint capability in MCNP, and provide examples and results indicating the effectiveness and validity of the MCNP multigroup/adjoint treatment. This information should assist users in taking advantage of the MCNP multigroup/adjoint capabilities.

  4. Capability 9.2 Mobility

    NASA Technical Reports Server (NTRS)

    Zakrasjek, June

    2005-01-01

    Modern operational concepts require significant bandwidths and multipoint communication capabilities. Provide voice, video and data communications among vehicles moving along the surface, vehicles in suborbital transport or reconnaissance, surface elements, and home planet facilities.

  5. SD46 Facilities and Capabilities

    NASA Technical Reports Server (NTRS)

    Ramachandran, N.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    The displays for the Materials Conference presents some of the facilities and capabilities in SD46 that can be useful to a prospective researcher from University, Academia or other government labs. Several of these already have associated personnel as principal and co-investigators on NASA peer reviewed science investigations. 1. SCN purification facility 2. ESL facility 3. Static and Dynamic magnetic field facility 4. Microanalysis facility 5. MSG Investigation - PFMI 6. Thermo physical Properties Measurement Capabilities.

  6. Earth Science Capability Demonstration Project

    NASA Technical Reports Server (NTRS)

    Cobleigh, Brent

    2006-01-01

    A viewgraph presentation reviewing the Earth Science Capability Demonstration Project is shown. The contents include: 1) ESCD Project; 2) Available Flight Assets; 3) Ikhana Procurement; 4) GCS Layout; 5) Baseline Predator B Architecture; 6) Ikhana Architecture; 7) UAV Capability Assessment; 8) The Big Picture; 9) NASA/NOAA UAV Demo (5/05 to 9/05); 10) NASA/USFS Western States Fire Mission (8/06); and 11) Suborbital Telepresence.

  7. Small cell foams containing a modified dense star polymer or dendrimer as a nucleating agent

    DOEpatents

    Hedstrand, D.M.; Tomalia, D.A.

    1995-02-28

    A small cell foam having a modified dense star polymer or dendrimer is described. This modified dense star polymer or dendrimer has a highly branched interior of one monomeric composition and an exterior structure of a different monomeric composition capable of providing a hydrophobic outer shell and a particle diameter of from about 5 to about 1,000 nm with a matrix polymer.

  8. Small cell foams containing a modified dense star polymer or dendrimer as a nucleating agent

    DOEpatents

    Hedstrand, David M.; Tomalia, Donald A.

    1995-01-01

    A small cell foam having a modified dense star polymer or dendrimer is described. This modified dense star polymer or dendrimer has a highly branched interior of one monomeric composition and an exterior structure of a different monomeric composition capable of providing a hydrophobic outer shell and a particle diameter of from about 5 to about 1,000 nm with a matrix polymer.

  9. Rational design of hyperbranched 3D heteroarrays of SrS/CdS: synthesis, characterization and evaluation of photocatalytic properties for efficient hydrogen generation and organic dye degradation

    NASA Astrophysics Data System (ADS)

    Khan, Ziyauddin; Chetia, Tridip Ranjan; Qureshi, Mohammad

    2012-05-01

    Hyperbranched 3D SrS/CdS nanostructures were synthesized using a one pot hydrothermal method. Transmission Electron Microscopy (TEM) and Field Emission-Scanning Electron Microscopy (FE-SEM) analysis showed the formation of flower-like structure and the crystalline phase was confirmed by powder X-ray diffraction. The prepared 3D SrS/CdS exhibited improved photocatalytic activity for water splitting leading to H2 generation (AQY 10%) and nearly complete degradation of methyl orange (MO) dye. The dye degradation followed first order kinetics and the apparent reaction rate constant (kapp) was 0.136 min-1. The present 3D SrS/CdS structure promise to be efficient photocatalysts due to (i) the facile intersystem charge transfer resulting from their band alignment (ii) enhanced specific surface area and (iii) crystallinity.Hyperbranched 3D SrS/CdS nanostructures were synthesized using a one pot hydrothermal method. Transmission Electron Microscopy (TEM) and Field Emission-Scanning Electron Microscopy (FE-SEM) analysis showed the formation of flower-like structure and the crystalline phase was confirmed by powder X-ray diffraction. The prepared 3D SrS/CdS exhibited improved photocatalytic activity for water splitting leading to H2 generation (AQY 10%) and nearly complete degradation of methyl orange (MO) dye. The dye degradation followed first order kinetics and the apparent reaction rate constant (kapp) was 0.136 min-1. The present 3D SrS/CdS structure promise to be efficient photocatalysts due to (i) the facile intersystem charge transfer resulting from their band alignment (ii) enhanced specific surface area and (iii) crystallinity. Electronic supplementary information (ESI) available: Schematic experimental setup for photocatalytic hydrogen generation, TEM of CdS NWs and SrS NPs, FESEM images of 3D SrS/CdS, Low resolution TEM images for 3D SrS/CdS, EDX and SAED, SEM of SrS/CdS at different ratios, progress of hydrogen production at different time interval, different UV

  10. Kernel CMAC with improved capability.

    PubMed

    Horváth, Gábor; Szabó, Tamás

    2007-02-01

    The cerebellar model articulation controller (CMAC) has some attractive features, namely fast learning capability and the possibility of efficient digital hardware implementation. Although CMAC was proposed many years ago, several open questions have been left even for today. The most important ones are about its modeling and generalization capabilities. The limits of its modeling capability were addressed in the literature, and recently, certain questions of its generalization property were also investigated. This paper deals with both the modeling and the generalization properties of CMAC. First, a new interpolation model is introduced. Then, a detailed analysis of the generalization error is given, and an analytical expression of this error for some special cases is presented. It is shown that this generalization error can be rather significant, and a simple regularized training algorithm to reduce this error is proposed. The results related to the modeling capability show that there are differences between the one-dimensional (1-D) and the multidimensional versions of CMAC. This paper discusses the reasons of this difference and suggests a new kernel-based interpretation of CMAC. The kernel interpretation gives a unified framework. Applying this approach, both the 1-D and the multidimensional CMACs can be constructed with similar modeling capability. Finally, this paper shows that the regularized training algorithm can be applied for the kernel interpretations too, which results in a network with significantly improved approximation capabilities. PMID:17278566

  11. Shape memory polymers

    DOEpatents

    Wilson, Thomas S.; Bearinger, Jane P.

    2015-06-09

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxyl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  12. Catalysts from synthetic genetic polymers

    PubMed Central

    Taylor, Alexander I.; Pinheiro, Vitor B.; Smola, Matthew J.; Morgunov, Alexey S.; Peak-Chew, Sew; Cozens, Christopher; Weeks, Kevin M.; Herdewijn, Piet; Holliger, Philipp

    2014-01-01

    The emergence of catalysis in early genetic polymers like RNA is considered a key transition in the origin of life1, predating the appearance of protein enzymes. DNA also demonstrates the capacity to fold into three-dimensional structures and form catalysts in vitro2. However, to what degree these natural biopolymers comprise functionally privileged chemical scaffolds3 for folding or the evolution of catalysis is not known. The ability of synthetic genetic polymers (XNAs) with alternative backbone chemistries not found in nature to fold into defined structures and bind ligands4 raises the possibility that these too might be capable of forming catalysts (XNAzymes). Here we report the discovery of such XNAzymes, elaborated in four different chemistries (ANA (arabino nucleic acids)5, FANA (2′-fluoroarabino nucleic acids)6, HNA (hexitol nucleic acids) and CeNA (cyclohexene nucleic acids)7 directly from random XNA oligomer pools, exhibiting in trans RNA endonuclease and ligase activities. We also describe an XNA-XNA ligase metalloenzyme in the FANA framework, establishing catalysis in an entirely synthetic system and enabling the synthesis of FANA oligomers and an active RNA endonuclease FANAzyme from its constituent parts. These results extend catalysis beyond biopolymers and establish technologies for the discovery of catalysts in a wide range of polymer scaffolds not found in nature8. Evolution of catalysis independent of any natural polymer has implications for the definition of chemical boundary conditions for the emergence of life on earth and elsewhere in the universe9. PMID:25470036

  13. Adjustable flow rate controller for polymer solutions

    DOEpatents

    Jackson, Kenneth M.

    1981-01-01

    An adjustable device for controlling the flow rate of polymer solutions which results in only little shearing of the polymer molecules, said device comprising an inlet manifold, an outlet manifold, a plurality of tubes capable of providing communication between said inlet and outlet manifolds, said tubes each having an internal diameter that is smaller than that of the inlet manifold and large enough to insure that viscosity of the polymer solution passing through each said tube will not be reduced more than about 25 percent, and a valve associated with each tube, said valve being capable of opening or closing communication in that tube between the inlet and outlet manifolds, each said valve when fully open having a diameter that is substantially at least as great as that of the tube with which it is associated.

  14. Covalent Polymers Containing Discrete Heterocyclic Anion Receptors

    PubMed Central

    Rambo, Brett M.; Silver, Eric S.; Bielawski, Christopher W.; Sessler, Jonathan L.

    2010-01-01

    This chapter covers recent advances in the development of polymeric materials containing discrete heterocyclic anion receptors, and focuses on advances in anion binding and chemosensor chemistry. The development of polymers specific for anionic species is a relatively new and flourishing area of materials chemistry. The incorporation of heterocyclic receptors capable of complexing anions through non-covalent interactions (e.g., hydrogen bonding and electrostatic interactions) provides a route to not only sensitive but also selective polymer materials. Furthermore, these systems have been utilized in the development of polymers capable of extracting anionic species from aqueous environments. These latter materials may lead to advances in water purification and treatment of diseases resulting from surplus ions. PMID:20871791

  15. Aqueous vinylidene fluoride polymer coating composition

    NASA Technical Reports Server (NTRS)

    Bartoszek, Edward J. (Inventor); Christofas, Alkis (Inventor)

    1978-01-01

    A water-based coating composition which may be air dried to form durable, fire resistant coatings includes dispersed vinylidene fluoride polymer particles, emulsified liquid epoxy resin and a dissolved emulsifying agent for said epoxy resin which agent is also capable of rapidly curing the epoxy resin upon removal of the water from the composition.

  16. Accelerator and electrodynamics capability review

    SciTech Connect

    Jones, Kevin W

    2010-01-01

    Los Alamos National Laboratory (LANL) uses capability reviews to assess the science, technology and engineering (STE) quality and institutional integration and to advise Laboratory Management on the current and future health of the STE. Capability reviews address the STE integration that LANL uses to meet mission requirements. The Capability Review Committees serve a dual role of providing assessment of the Laboratory's technical contributions and integration towards its missions and providing advice to Laboratory Management. The assessments and advice are documented in reports prepared by the Capability Review Committees that are delivered to the Director and to the Principal Associate Director for Science, Technology and Engineering (PADSTE). Laboratory Management will use this report for STE assessment and planning. LANL has defined fifteen STE capabilities. Electrodynamics and Accelerators is one of the seven STE capabilities that LANL Management (Director, PADSTE, technical Associate Directors) has identified for review in Fiscal Year (FY) 2010. Accelerators and electrodynamics at LANL comprise a blend of large-scale facilities and innovative small-scale research with a growing focus on national security applications. This review is organized into five topical areas: (1) Free Electron Lasers; (2) Linear Accelerator Science and Technology; (3) Advanced Electromagnetics; (4) Next Generation Accelerator Concepts; and (5) National Security Accelerator Applications. The focus is on innovative technology with an emphasis on applications relevant to Laboratory mission. The role of Laboratory Directed Research and Development (LDRD) in support of accelerators/electrodynamics will be discussed. The review provides an opportunity for interaction with early career staff. Program sponsors and customers will provide their input on the value of the accelerator and electrodynamics capability to the Laboratory mission.

  17. Polymer Energy Rechargeable System Battery Being Developed

    NASA Technical Reports Server (NTRS)

    Manzo, Michelle A.

    2003-01-01

    Long description. Illustrations of discotic liquid crystals, rod-coil polymers, lithium-ion conducting channel dilithium phthalocyanine (Li2Pc) from top and side, novel star polyethylene oxide structures, composite polyethylene oxide materials (showing polyethylene oxide + lithium salt, carbon atoms and oxygen atoms), homopolyrotaxanes, and diblock copolymers In fiscal year 2000, NASA established a program to develop the next generation, lithium-based, polymer electrolyte batteries for aerospace applications. The goal of this program, known as Polymer Energy Rechargeable Systems (PERS), is to develop a space-qualified, advanced battery system embodying polymer electrolyte and lithium-based electrode technologies and to establish world-class domestic manufacturing capabilities for advanced batteries with improved performance characteristics that address NASA s future aerospace battery requirements.

  18. Conducting polymer membranes as intelligent separation systems

    SciTech Connect

    Price, W.E.; Wallace, G.G.

    1994-12-31

    Conducting electroactive polymers such as polypyrroles, are emerging as excellent materials in which to base a generic technology for the development of intelligent material systems. They are easy to make and many different chemistries may be built in during synthesis by varying the polymer(s) used and the counterions incorporated. However, the unique feature about them is that they have dynamic chemical and physical properties which may be manipulated via changing the redox states after synthesis. This paper illustrates their potential using recent work on developing a new electro-membrane separation technology using free-standing polypyrrole films. These systems are shown to be capable of a high degree of permselectivity and controllable transport that may be turned on and off by application of potential to the conducting polymer membrane.

  19. Vacuum deposited polymer/silver reflector material

    SciTech Connect

    Affinito, J.; Martin, P.; Gross, M.; Bennett, W.

    1994-07-01

    Weatherable, low cost, front surface, solar reflectors on flexible substrates would be highly desirable for lamination to solar concentrator panels. The method to be described in this paper may permit such reflector material to be fabricated for less than 50 cents per square foot. Vacuum deposited Polymer/Silver/Polymer reflectors and Fabry-Perot interference filters were fabricated in a vacuum web coating operation on polyester substrates. Reflectivities were measured in the wavelength range from .4 {mu}m to .8 {mu}m. It is hoped that a low cost substrate can be used with the substrate laminated to the concentrator and the weatherable acrylic polymer coating facing the sun. This technique should be capable of deposition line speeds approaching 1500 linear feet/minute. Central to this technique is a new vacuum deposition process for the high rate deposition of polymer films. This polymer process involves the flash evaporation of an acrylic monomer onto a moving substrate. The monomer is subsequently cured by an electron beam or ultraviolet light. This high speed polymer film deposition process has been named the PML process - for Polymer Multi-Layer.

  20. Natural Environment Capabilities at MSFC

    NASA Technical Reports Server (NTRS)

    Parker, Linda Neergaard; Willis, Emily M.; Minow, Joseph I.

    2014-01-01

    The Natural Environments Branch at Marshall Space Flight Center is integral in developing, maintaining, and investigating NASA missions such as Space Launch Systems (SLS), currently under development, as well as many NASA and other agency satellite missions. We present the space environment capabilities of the Natural Environments Branch at MSFC. These in-house capabilities include model development, analysis of space and terrestrial related data, spacecraft charging anomaly investigations, surface charging modeling including Nascap-2k, space environment definition and radiation parts assessment. All aspects of space and terrestrial design are implemented with the goal of devising missions to be successful at launch and in the space environment of LEO, polar, GEO, and interplanetary orbits. In this poster, we show examples of recent applications of branch capabilities to NASA missions.

  1. Star-Shaped Amphiphilic Hyperbranched Polyglycerol Conjugated with Dendritic Poly(l-lysine) for the Codelivery of Docetaxel and MMP-9 siRNA in Cancer Therapy.

    PubMed

    Zhou, Xiaoyan; Zheng, Qianqian; Wang, Changyong; Xu, Jiake; Wu, Jian-Ping; Kirk, Thomas Brett; Ma, Dong; Xue, Wei

    2016-05-25

    The drug/gene codelivery is a promising strategy for cancer treatment. Herein, to realize the codelivery of docetaxel and MMP-9 siRNA plasmid efficiently into tumor cells, a star-shaped amphiphilic copolymer consisting of hyperbranched polyglycerol derivative (HPG-C18) and dendritic poly(l-lysine) (PLLD) was synthesized by the click reaction between azido-modified HPG-C18 and propargyl focal point PLLD. The obtained HPG-C18-PLLD could form the nanocomplexes with docetaxel and MMP-9, and the complexes showed good gene delivery ability in vitro by inducing an obvious decrease in MMP-9 protein expression in MCF-7 cells. The apoptosis assay showed that the complex could induce a more significant apoptosis to breast cancer cells than that of docetaxel or MMP-9 used alone. In vivo assay indicated that the codelivery strategy displayed a better effect on tumor inhibition. Moreover, HPG-C18-PLLD displayed lower toxicity as well as better blood compatibility compared to polyethylenimine PEI-25k, which may be the result of that HPG-C18-PLLD showed the comparative MMP-9 delivery ability in vivo compared with PEI-25k even if it showed the slight lower transfection efficiency in vitro. Therefore, HPG-C18-PLLD is a safe and effective carrier for the codelivery of drug/gene, which should be encouraged in tumor therapy. PMID:27153187

  2. Spectroscopic investigation on the interaction of hyperbranched poly (amine) ester with model plasma protein: Effect on the structural and conformational changes

    NASA Astrophysics Data System (ADS)

    Xiao, Fengjuan; Gu, Muqing; Liang, Ye; Li, Lanlan; Luo, Yunjun

    2014-01-01

    Mechanism of interaction between hyperbranched poly (amine) ester (HPAE) and bovine serum albumin (BSA) was investigated using fluorescence, synchronous fluorescence, three-dimensional fluorescence spectra, UV-Vis spectrometry and circular dichroism (CD). The structural and conformational changes of BSA induced by HPAE were also revealed in this study. Stern-Volmer analysis of fluorescence quenching showed that BSA fluorescence was statically quenched by HPAE, which implied that ground state complex formed between BSA and HPAE. Vander Waals force and hydrogen bond played major roles in the interaction of HPAE with BSA. The distance, r between the donor (BSA) and acceptor (HPAE) was calculated based on the Forster's theory of non-radiation energy transfer and was found to be 3.24 nm. Synchronous and three-dimensional fluorescence studies showed that the interaction of BSA with HPAE induced conformational changes in BSA. The secondary structural analysis by CD spectra suggested that HPAE binding induced BSA to form a more compact conformation with about 6.9% transformation of α-helix to β-sheet. Molecular model of the interaction of HPAE with BSA was also presented according to the results of this study.

  3. In vitro and in vivo evaluation of stimuli-responsive vesicle from PEGylated hyperbranched PAMAM-doxorubicin conjugate for gastric cancer therapy.

    PubMed

    Nie, Jinshan; Wang, Yang; Wang, Wei

    2016-07-25

    Gastric Cancer is one of the major leading causes of death by cancer worldwide, but the chemotherapeutics, one of the preferred approaches, bring about extensive side effects when systemically injected. In our work, doxorubicin-loaded pH and redox responsive hyperbranched poly(amidoamine)(h-PAMAM)-based vesicle was prepared to enhance anti-tumor efficacy of chemotherapeutic compounds. The doxorubicin (DOX) molecules were attached to PEGylated h-PAMAM by acid sensitive cis-aconityl linkage to form pH sensitive conjugate (PPCD), which self-assembled in THF into micelles. The resulted micelles were then crosslinked by disulfide bonds and transferred from THF into water to form vesicles, which could be disassembled into small-sized conjugates under the redox condition. The drug release profiles showed that the PPCD vesicle presented stimuli-triggered drug release in acidic and reducing environment, and lower DOX leakage under neutral condition. The in vitro cell assay reflected the rapid DOX release and significant tumor-cytotoxic effect of the PPCD vesicle. The in vivo anticancer activity and systematic toxicity studies showed that the PPCD vesicles had lower tissue toxicity with good antitumor effect. In brief, h-PAMAM-based PPCD vesicle provides a safe and effective drug delivery system for the therapy of gastric cancer. PMID:27234696

  4. Hyperbranched fluoropolymer-polydimethylsiloxane-poly(ethylene glycol) cross-linked terpolymer networks designed for marine and biomedical applications: heterogeneous nontoxic antibiofouling surfaces.

    PubMed

    Pollack, Kevin A; Imbesi, Philip M; Raymond, Jeffery E; Wooley, Karen L

    2014-01-01

    Synthesis of terpolymer coatings composed of hyperbranched fluoropolymers cross-linked with bisamino-propyl poly(ethylene glycol) and bisamino-propyl polydimethylsiloxane (PDMS) was performed to generate antibiofouling surfaces. Nanoscale imaging and surface spectroscopy confirmed that this system possessed complex surface topographies and chemical compositions. Surface complexity was determined to be due to molecular interactions, phase segregation, and compositional gradients arising between the three components. A clear difference in surface behavior was observable before and after exposure to water. Antibiofouling characteristics were investigated by bovine serum albumin (BSA) adsorption studies; the terpolymer coating displayed a 60% greater resistance to protein adsorption in comparison to the fouling of a commercial antibiofouling silicone coating. The unique surface topography, topology, and chemical heterogeneity expressed at a variety of scales provide a robust regime for the generation of hardy, complex surfaces known to incorporate characteristics appropriate for antibiofouling applications. Thorough assessment of thermal responses and mechanical properties in relevant environments demonstrated a formulation platform immediately appropriate for consideration in marine and in vivo applications. PMID:25329934

  5. Ultrasensitive electrochemical biosensor for specific detection of DNA based on molecular beacon mediated circular strand displacement polymerization and hyperbranched rolling circle amplification.

    PubMed

    Li, Xiaolu; Guo, Jing; Zhai, Qian; Xia, Jing; Yi, Gang

    2016-08-31

    Using a cascade signal amplification strategy, an ultrasensitive electrochemical biosensor for specific detection of DNA based on molecular beacon (MB) mediated circular strand displacement polymerization (CSDP) and hyperbranched rolling circle amplification (HRCA) was proposed. The hybridization of MB probe to target DNA resulted in a conformational change of the MB and triggered the CSDP in the presence of bio-primer and Klenow fragment (KF exo(-)), leading to multiple biotin-tagged DNA duplex. Furthermore, the HRCA was implemented to product amounts of double-stranded DNA (ds-DNA) fragments using phi29 DNA polymerase via biotin-streptavidin interaction. After the product of HRCA binded numerous biotinylated detection probes, an ultrasensitive electrochemical readout by further employing the streptavidin-alkaline phosphatase. The proposed biosensor exhibited excellent detection sensitivity and specificity with a log-linear response to target DNA from 0.01 fM to 10 pM as low as 8.9 aM. The proposed method allowed DNA detection with simplicity, rapidness, low cost and high specificity, which might have the potential for application in clinical molecular diagnostics and environmental monitoring. PMID:27506343

  6. Loop polymer brushes from polymer single crystals

    NASA Astrophysics Data System (ADS)

    Zhou, Tian; Li, Christopher

    2014-03-01

    Loop polymer brushes represent a category of polymer brushes with both chain ends being tethered to a surface or interface with sufficiently high density. Due to this morphological difference, loop brushes exhibit distinct properties compared with traditional polymer brushes with single chain end being tethered. In our study, α, ω-functionalized polycaprolactone (PCL) single crystals were prepared as templates for polymer brush synthesis. By carefully controlling crystallization condition and immobilization, looped polymer brushes were successfully prepared. Comprehensive studies on the morphology and physical properties of these polymer brushes were carried out using Atomic Force Microscopy and FTIR. Advantages of using this method include exclusive loop morphology, high grafting density, controlled tethering sites and tunable loop size.

  7. Radioluminescent light sources, tritium containing polymers, and methods for producing the same

    DOEpatents

    Jensen, G.A.; Nelson, D.A.; Molton, P.M.

    1989-12-26

    A radioluminescent light source comprises a solid mixture of a phosphorescent substance and a tritiated polymer. The solid mixture forms a solid mass having length, width, and thickness dimensions, and is capable of self-support. In one aspect of the invention, the phosphorescent substance comprises solid phosphor particles supported or surrounded within a solid matrix by a tritium containing polymer. The tritium containing polymer comprises a polymer backbone which is essentially void of tritium. 2 figs.

  8. Radioluminescent light sources, tritium containing polymers, and methods for producing the same

    DOEpatents

    Jensen, George A.; Nelson, David A.; Molton, Peter M.

    1989-01-01

    A radioluminescent light source comprises a solid mixture of a phosphorescent substance and a tritiated polymer. The solid mixture forms a solid mass having length, width, and thickness dimensions, and is capable of self-support. In one aspect of the invention, the phosphorescent substance comprises solid phosphor particles supported or surrounded within a solid matix by a tritium containing polymer. The tritium containing polymer comprises a polymer backbone which is essentially void of tritium.

  9. Rheology of cross-linked polymers and polymer foams: Theory and experimental results

    NASA Astrophysics Data System (ADS)

    Herman, John N.

    Typical polymers have a time-dependent response to loading which results in stress relaxation or creep. Models using springs/dashpots or Volterra integrals are capable of predicting the material response, but place little or no emphasis on the reasoning behind the response. This research proposes a microscopic reasoning behind polymer chain movement, while developing a model to predict the creep and stress relaxation of a polymer foam. Based on the theorized slip/stick of polymer chains as they slide past each other, this model successfully predicts the behavior of a PMI polymer foam under tensile loads. This model lends insights into polymer microscopic behavior, which may be used for the development of future polymer materials. When possible, industry standard test methods are used to obtain tensile creep and stress relaxation results from rectangular specimens of Rohacell 31 IG foam. A common set of material parameters is fitted to the data, validating the micromechanic reasoning to polymer chain movement. To gain insight into observed test result variability, an investigation of the elastic modulus and material density relationship is performed using nominal foam densities of 31 kg/m3, 51 kg/m3,, 71 kg/m3. Additional testing and modeling is performed to validate the model under load/partial-unload/ hold, load/unload/recovery, and load/instantaneous-unload test cycles. The model successfully captures the observed material nuances during these more complex loading cycles.

  10. Polymer Functionalized Nanoparticles in Polymer Nanocomposites

    NASA Astrophysics Data System (ADS)

    Jayaraman, Arthi

    2013-03-01

    Significant interest has grown around the ability to control spatial arrangement of nanoparticles in a polymer nanocomposite to engineer materials with target properties. Past work has shown that one could achieve controlled assembly of nanoparticles in the polymer matrix by functionalizing nanoparticle surfaces with homopolymers. This talk will focus on our recent work using Polymer Reference Interaction Site Model (PRISM) theory and Monte Carlo simulations and GPU-based molecular dynamics simulations to specifically understand how heterogeneity in the polymer functionalization in the form of a) copolymers with varying monomer chemistry and monomer sequence, and b) polydispersity in homopolymer grafts can tune effective interactions between functionalized nanoparticles, and the assembly of functionalized nanoparticles.

  11. Interfacial behavior of polymer electrolytes

    SciTech Connect

    Kerr, John; Kerr, John B.; Han, Yong Bong; Liu, Gao; Reeder, Craig; Xie, Jiangbing; Sun, Xiaoguang

    2003-06-03

    Evidence is presented concerning the effect of surfaces on the segmental motion of PEO-based polymer electrolytes in lithium batteries. For dry systems with no moisture the effect of surfaces of nano-particle fillers is to inhibit the segmental motion and to reduce the lithium ion transport. These effects also occur at the surfaces in composite electrodes that contain considerable quantities of carbon black nano-particles for electronic connection. The problem of reduced polymer mobility is compounded by the generation of salt concentration gradients within the composite electrode. Highly concentrated polymer electrolytes have reduced transport properties due to the increased ionic cross-linking. Combined with the interfacial interactions this leads to the generation of low mobility electrolyte layers within the electrode and to loss of capacity and power capability. It is shown that even with planar lithium metal electrodes the concentration gradients can significantly impact the interfacial impedance. The interfacial impedance of lithium/PEO-LiTFSI cells varies depending upon the time elapsed since current was turned off after polarization. The behavior is consistent with relaxation of the salt concentration gradients and indicates that a portion of the interfacial impedance usually attributed to the SEI layer is due to concentrated salt solutions next to the electrode surfaces that are very resistive. These resistive layers may undergo actual phase changes in a non-uniform manner and the possible role of the reduced mobility polymer layers in dendrite initiation and growth is also explored. It is concluded that PEO and ethylene oxide-based polymers are less than ideal with respect to this interfacial behavior.

  12. Re-Mendable Polymers

    NASA Astrophysics Data System (ADS)

    Bergman, Sheba D.; Wudl, Fred

    Polymers have become an indispensable material resource, representing billions of dollars worth of material consumption every year. The rising prices and exhaust of natural resources such as petroleum, combined with rising environmental concerns, have prompted the development of recyclable and degradable polymers. Polymers that can be reverted back to their monomers or to shorter repolymerizable oligomers, hence, reversible polymers are particularly enticing in this respect because they essentially prevent any material loss with multiple recycling. While reversible polymers have been known for a long time, there has been recent renewed interest in such polymers, since their reversibility can be exploited for repair at the molecular level.

  13. Lipid-absorbing Polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr.; Wallace, C. J.

    1973-01-01

    The removal of bile acids and cholesterol by polymeric absorption is discussed in terms of micelle-polymer interaction. The results obtained with a polymer composed of 75 parts PEO and 25 parts PB plus curing ingredients show an absorption of 305 to 309%, based on original polymer weight. Particle size effects on absorption rate are analyzed. It is concluded that crosslinked polyethylene oxide polymers will absorb water, crosslinked polybutadiene polymers will absorb lipids; neither polymer will absorb appreciable amounts of lipids from micellar solutions of lipids in water.

  14. The People Capability Maturity Model

    ERIC Educational Resources Information Center

    Wademan, Mark R.; Spuches, Charles M.; Doughty, Philip L.

    2007-01-01

    The People Capability Maturity Model[R] (People CMM[R]) advocates a staged approach to organizational change. Developed by the Carnegie Mellon University Software Engineering Institute, this model seeks to bring discipline to the people side of management by promoting a structured, repeatable, and predictable approach for improving an…

  15. Capability and Learning to Choose

    ERIC Educational Resources Information Center

    LeBmann, Ortrud

    2009-01-01

    The Capability Approach (henceforth CA) is in the first place an approach to the evaluation of individual well-being and social welfare. Many disciplines refer to the CA, first and foremost welfare economics, development studies and political philosophy. Educational theory was not among the first disciplines that took notice of the CA, but has a…

  16. Demonstration of new PCSD capabilities

    NASA Technical Reports Server (NTRS)

    Gough, M.

    1986-01-01

    The new, more flexible and more friendly graphics capabilities to be available in later releases of the Pilot Climate Data System were demonstrated. The LIMS-LAMAT data set was chosen to illustrate these new capabilities. Pseudocolor and animation were used to represent the third and fourth dimensions, expanding the analytical capabilities available through the traditional two-dimensional x-y plot. In the new version, variables for the axes are chosen by scrolling through viable selections. This scrolling feature is a function of the new user interface customization. The new graphics are extremely user friendly and should free the scientist to look at data and converse with it, without doing any programming. The system is designed to rapidly plot any variable versus any other variable and animate by any variable. Any one plot in itself is not extraordinary; however, the fact that a user can generate the plots instead of a programmer distinguishes the graphics capabilities of the PCDS from other software packages. In addition, with the new CDF design, the system will become more generic, and the new graphics will become much more rigorous in the area of correlative studies.

  17. Research for new UAV capabilities

    SciTech Connect

    Canavan, G.H.; Leadabrand, R.

    1996-07-01

    This paper discusses research for new Unmanned Aerial Vehicles (UAV) capabilities. Findings indicate that UAV performance could be greatly enhanced by modest research. Improved sensors and communications enhance near term cost effectiveness. Improved engines, platforms, and stealth improve long term effectiveness.

  18. Medical vest broadens treatment capability

    NASA Technical Reports Server (NTRS)

    Johnson, G. S.

    1970-01-01

    Universal sized vest, with specially tailored pockets designed to hold medical supplies, provides first aid/first care medical teams with broadened on-site capability. Vest is made of nylon, tough fibrous materials, and polyvinyl chloride. Design facilitates rapid donning, doffing, and adjustment.

  19. Overview of composites capability at Lawrence Livermore National Laboratory

    SciTech Connect

    Lepper, J.K.

    1983-08-30

    LLNL has had a polymer matrix fiber composite research and development activity for over twenty years. LLNL has an active multidisciplined team investigating all aspects of polymer matrix fiber composites. This is a unique national resource because it is a total capability from the synthesis of new materials to the manufacture of final products. We have concentrated our research and development efforts on high performance structural composites. The materials are used in critical components requiring service reliability certifications of from 10/sup -3/ to 10/sup -6/ failure probabilities. Many of these components are designed to function in severe service environments for more than twenty-five years. Our approach to accomplishing these objectives has been to establish a very large and sound data base. Using this data base we have developed a fundamental understanding of glass, graphite, and aramid fibers, epoxy and polyimide matrices, and their high performance structural composites.

  20. Nonlinear Optics in Novel Polymer Systems.

    NASA Astrophysics Data System (ADS)

    Li, Lian

    Polymeric nonlinear optical (NLO) materials have recently attracted considerable attention and been the subject of intensive investigations. Polymeric NLO materials possessing large second and third order NLO properties, ultrafast response times, high optical damage threshold, transparency over a broad wavelength range, and capability to be easily processed into good optical quality thin films, offer significant advantages over the traditional inorganic materials for applications in fabricating integrated optical devices, such as waveguide electro-optic (EO) modulators and optical frequency doublers, and optical signal processing devices. This dissertation presents the experimental investigations on novel NLO polymers synthesized in the Laboratory of Electronic and Photonic Materials at University of Massachusetts Lowell. Progress made for the past few years on polymeric NLO materials is reviewed, especially with regard to the second order NLO properties of the polymeric materials. Two novel stable second order NLO polymer systems, an interpenetrating polymer network (IPN) formed via thermal crosslinking and a sol-gel process, and a photocrosslinkable conducting polymer, upon poling and crosslinking, exhibited large and stable second order NLO properties measured for these polymers by using the second harmonic generation (SHG) technique. For the IPN system, the SHG measurements as a function of time at several elevated temperatures indicate the superb stability of the second order NLO properties. For the conducting NLO polymer, the NLO property of the poled and photocrosslinked polymer film is stable at room temperature. The wavelength shifting of a Q-switched Nd:YAG laser by stimulated Raman scattering is also described. Measurements were made on the third order NLO properties of a dye doped photocrosslinkable guest-host polymer system at different dye concentrations with a modified Michelson interferometer. By functionalizing the dye to make it more compatible to

  1. Photofabrication of surface relief gratings using post functionalized azo polymers

    SciTech Connect

    Tripathy, S.K.; Kumar, J.; Kim, D.Y.; Jiang, X.; Wang, X.; Li, L.; Sukwattanasinitt, M.; Sandman, D.J.

    1998-07-01

    A series of azobenzene funtionalized polymers has been synthesized by post polymerization azo coupling reaction. Photo-fabrication of surface relief gratings were studied on the polymer films. Epoxy based azo polymers were prepared by post azo coupling reaction to form polymers containing donor-acceptor type azo chromophores. The azo chromophores were designed to contain ionizable groups to impart self-assembling and photoprocessing capabilities to the polymers. The polymers containing 4-(4-(carboxylic acid)phenylazo)aniline chromophores can be directly photofabricated to form surface relief gratings with large surface modulations. Charge interactions had a strong influence on the details of the writing process. A new soluble polydiacetylene, post-functionalized with azobenzene groups was also prepared. Large amplitude surface gratings could be fabricated on this polydiacetylene film as well.

  2. Polymer-Polymer Bilayer Actuator

    NASA Technical Reports Server (NTRS)

    Su, Ji (Inventor); Harrison, Joycelyn S. (Inventor); St.Clair, Terry L. (Inventor)

    2003-01-01

    A device for providing an electromechanical response includes two polymeric webs bonded to each other along their lengths. At least one polymeric web is activated upon application thereto of an electric field and exhibits electrostriction by rotation of polar graft moieties within the polymeric web. In one embodiment, one of the two polymeric webs in an active web upon application thereto of the electric field, and the other polymeric web is a non-active web upon application thereto of the electric field. In another embodiment, both of the two polymeric webs are capable of being active webs upon application thereto of the electric field. However, these two polymeric webs are alternately activated and non-activated by the electric field.

  3. Playing with Polymers.

    ERIC Educational Resources Information Center

    Chemecology, 1997

    1997-01-01

    Presents an activity that enables students to gain a better understanding of the importance of polymers. Students perform an experiment in which polymer chains of polyvinyl acetate form crosslinks. Includes background information and discussion questions. (DDR)

  4. Introduction to Polymer Chemistry.

    ERIC Educational Resources Information Center

    Harris, Frank W.

    1981-01-01

    Reviews the physical and chemical properties of polymers and the two major methods of polymer synthesis: addition (chain, chain-growth, or chain-reaction), and condensation (step-growth or step-reaction) polymerization. (JN)

  5. Anion exchange polymer electrolytes

    SciTech Connect

    Kim, Yu Seung; Kim, Dae Sik

    2015-06-02

    Anion exchange polymer electrolytes that include guanidinium functionalized polymers may be used as membranes and binders for electrocatalysts in preparation of anodes for electrochemical cells such as solid alkaline fuel cells.

  6. Polymer composites containing nanotubes

    NASA Technical Reports Server (NTRS)

    Bley, Richard A. (Inventor)

    2008-01-01

    The present invention relates to polymer composite materials containing carbon nanotubes, particularly to those containing singled-walled nanotubes. The invention provides a polymer composite comprising one or more base polymers, one or more functionalized m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers and carbon nanotubes. The invention also relates to functionalized m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers, particularly to m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers having side chain functionalization, and more particularly to m-phenylenevinylene-2,5-disubstituted-p-phenylenevinylene polymers having olefin side chains and alkyl epoxy side chains. The invention further relates to methods of making polymer composites comprising carbon nanotubes.

  7. Polymer Fluid Dynamics.

    ERIC Educational Resources Information Center

    Bird, R. Byron

    1980-01-01

    Problems in polymer fluid dynamics are described, including development of constitutive equations, rheometry, kinetic theory, flow visualization, heat transfer studies, flows with phase change, two-phase flow, polymer unit operations, and drag reduction. (JN)

  8. Improving the RPC rate capability

    NASA Astrophysics Data System (ADS)

    Aielli, G.; Camarri, P.; Cardarelli, R.; Di Ciaccio, A.; Di Stante, L.; Iuppa, R.; Liberti, B.; Paolozzi, L.; Pastori, E.; Santonico, R.; Toppi, M.

    2016-07-01

    This paper has the purpose to study the rate capability of the Resistive Plate Chamber, RPC, starting from the basic physics of this detector. The effect of different working parameters determining the rate capability is analysed in detail, in order to optimize a new family of RPCs for applications to heavy irradiation environments and in particular to the LHC phase 2. A special emphasis is given to the improvement achievable by minimizing the avalanche charge delivered in the gas. The paper shows experimental results of Cosmic Ray tests, performed to study the avalanche features for different gas gap sizes, with particular attention to the overall delivered charge. For this purpose, the paper studies, in parallel to the prompt electronic signal, also the ionic signal which gives the main contribution to the delivered charge. Whenever possible the test results are interpreted on the basis of the RPC detector physics and are intended to extend and reinforce our physical understanding of this detector.

  9. Advanced Power System Analysis Capabilities

    NASA Technical Reports Server (NTRS)

    1997-01-01

    As a continuing effort to assist in the design and characterization of space power systems, the NASA Lewis Research Center's Power and Propulsion Office developed a powerful computerized analysis tool called System Power Analysis for Capability Evaluation (SPACE). This year, SPACE was used extensively in analyzing detailed operational timelines for the International Space Station (ISS) program. SPACE was developed to analyze the performance of space-based photovoltaic power systems such as that being developed for the ISS. It is a highly integrated tool that combines numerous factors in a single analysis, providing a comprehensive assessment of the power system's capability. Factors particularly critical to the ISS include the orientation of the solar arrays toward the Sun and the shadowing of the arrays by other portions of the station.

  10. Fan Flutter Analysis Capability Enhanced

    NASA Technical Reports Server (NTRS)

    Bakhle, Milind A.; Srivastava, Rakesh; Stefko, George L.

    2001-01-01

    The trend in the design of advanced transonic fans for aircraft engines has been toward the use of complex high-aspect-ratio blade geometries with a larger number of blades and higher loading. In addition, integrally bladed disks or blisks are being considered in fan designs for their potential to reduce manufacturing costs, weight, and complexity by eliminating attachments. With such design trends, there is an increased possibility within the operating region of part-speed stall flutter (self-excited vibrations) that is exacerbated by the reduced structural damping of blisk fans. To verify the aeroelastic soundness of the design, the NASA Glenn Research Center is developing and validating an accurate aeroelastic prediction and analysis capability. Recently, this capability was enhanced significantly as described here.

  11. LOFT Augmented Operator Capability Program

    SciTech Connect

    Hollenbeck, D.A.; Krantz, E.A.; Hunt, G.L.; Meyer, O.R.

    1980-01-01

    The outline of the LOFT Augmented Operator Capability Program is presented. This program utilizes the LOFT (Loss-of-Fluid Test) reactor facility which is located at the Idaho National Engineering Laboratory and the LOFT operational transient experiment series as a test bed for methods of enhancing the reactor operator's capability for safer operation. The design of an Operational Diagnotics and Display System is presented which was backfit to the existing data acquisition computers. Basic color-graphic displays of the process schematic and trend type are presented. In addition, displays were developed and are presented which represent safety state vector information. A task analysis method was applied to LOFT reactor operating procedures to test its usefulness in defining the operator's information needs and workload.

  12. Diamond Machining Applications And Capabilities

    NASA Astrophysics Data System (ADS)

    Benjamin, Roland J.

    1983-12-01

    Aspheric surface generation and precision machining have been important technologies at Hughes Optical Products, Inc. (formerly Optical Division, Bell & Howell Company) for over twenty years. Present machining capabilities and supporting services which are available on a custom basis are described. A variety of applications of diamond machining are illustrated, involving not only the usual reflective materials such as aluminum, copper, and electroless nickel but also such IR refractive materials as germanium, silicon, and chalcogenide glasses.

  13. Instrumentation: Analytical Capabilities on Mars

    NASA Technical Reports Server (NTRS)

    Westall, Frances; Allen, Carl; Braiser, Martin; Farmer, Jack; Massell, Wulf; Agee, Carl B.; Steele, Andrew; Fortson, Russ

    1998-01-01

    Human exploration of Mars will consist of a series of long-term missions, with early missions focusing upon establishing the Mars base, and undertaking basic field reconnaissance. A capable laboratory on Mars is an essential element in the exploration strategy. Analytical equipment both in the field and in the laboratory serves to extend the senses of the crew and help them sharpen their sampling skills as they learn to recognize rocks in the field and understand their geologic context and significance. On-site sample analyses allow results to be incorporated into evolving surface exploration plans and strategies, which will be developing in real-time as we learn more about Mars. Early Mars missions will focus on reconnaissance EVAs to collect rock and soil samples, maximizing the amount of Mars material returned to Earth. Later missions will be increasingly devoted to both extensive field campaigns and laboratory analyses. The capabilities and equipment described below will be built up at the Mars base incrementally over many missions, with science payloads and investigative infrastructure being partitioned among launch opportunities. This discussion considers what we require to measure, observe, and explore on a new planetary territory. Alternatively, what do we need to know and how do we equip ourselves to provide ample capabilities to acquire these data? Suggestions follow describing specific instruments that we could use. Appendix 5 lists a strawman science instrument payload, and a feasibility study of equipment transportation into the field on pressurized or unpressurized rovers.

  14. Exploration Medical Capability - Technology Watch

    NASA Technical Reports Server (NTRS)

    Krihak, Michael; Watkins, Sharmila; Barr, Yael; Barsten, Kristina; Fung, Paul; Baumann, David

    2011-01-01

    The objectives of the Technology Watch process are to identify emerging, high-impact technologies that augment current ExMC development efforts, and to work with academia, industry, and other government agencies to accelerate the development of medical care and research capabilities for the mitigation of potential health issues that could occur during space exploration missions. The establishment of collaborations with these entities is beneficial to technology development, assessment and/or insertion. Such collaborations also further NASA s goal to provide a safe and healthy environment for human exploration. The Tech Watch project addresses requirements and capabilities identified by knowledge and technology gaps that are derived from a discrete set of medical conditions that are most likely to occur on exploration missions. These gaps are addressed through technology readiness level assessments, market surveys, collaborations and distributed innovation opportunities. Ultimately, these gaps need to be closed with respect to exploration missions, and may be achieved through technology development projects. Information management is a key aspect to this process where Tech Watch related meetings, research articles, collaborations and partnerships are tracked by the HRP s Exploration Medical Capabilities (ExMC) Element. In 2011, ExMC will be introducing the Tech Watch external website and evidence wiki that will provide access to ExMC technology and knowledge gaps, technology needs and requirements documents.

  15. Spherically shaped micron-size particle-reinforced PMMA and PC composites for improving energy absorption capability

    NASA Astrophysics Data System (ADS)

    Kim, Hyung-ick; Kang, Eung-Chun; Jang, Jae-Soon; Suhr, Jonghwan

    2011-04-01

    The focus of this study was to experimentally investigate spherically shaped micron-size particles reinforced polymethyl methacrylate (PMMA) and polycarbonate (PC) polymer composites for improving energy absorbing capabilities such as toughness and low-velocity impact resistance. In this study, a solution mixing method was developed to fabricate both PMMA and PC polymer composites with spherically shaped micron-size polyamide- nylon 6 (PA6) particles inclusions. The morphology of the fracture surfaces of polymer composites was examined by using optical microscopy and scanning electron microscopy. Strain-rate dependent response of both PMMA and PC polymer composites was investigated by characterizing tensile and flexural properties. Low-velocity penetration testing was performed for both polymer composites and the key results observed for energy absorption capabilities are discussed in this study.

  16. Polymer Surface Melting Mediated by Capillary Waves

    NASA Astrophysics Data System (ADS)

    Herminghaus, Stephan; Seemann, Ralf; Landfester, Katharina

    2004-07-01

    Nuclear magnetic resonance investigations of atactic polystyrene emulsions yield direct evidence that the polymer surface exhibits a rather well-defined molten layer. Its thickness d grows continuously as the temperature is increased towards the bulk glass transition, according to d∝(Tg-T)-1. This is precisely what was recently predicted by a simple continuum model considering viscoelastic surface waves. Furthermore, this model is capable of explaining the frequently reported depression of the glass transition temperature in thin polymer films, and thus suggests a quite simple mechanism to underlie all these effects.

  17. 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. PMID:25647481

  18. Metal-polymer and polymer-polymer interfaces: Application to conjugated polymer electronic devices

    NASA Astrophysics Data System (ADS)

    Smallfield, Julie Anne Osladil

    The study of metal-polymer and polymer-polymer interfaces is applied to conjugated polymer electronic devices. Conjugated polymers are a class of organic materials which have metallic or semiconducting properties which are being investigated as alternatives to traditional semiconducting materials. When conjugated polymers are used in devices, the interfaces are found to be critical to device performance. X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS), which give information about the atomic and chemical composition, workfunction, and ionization potential of materials, are used to study these interfaces. In studying metal-polymer interfaces, it is shown that the interface between the conjugated polymer fully sulfonated polyaniline (NSPAN) and an aluminum alloy is an active interface, in which copper is extracted by the polymer from the aluminum alloy. This results in the aluminum alloy becoming more resistant to corrosion in a salty environment. The interface between aluminum and NSPAN, as it is found in some light emitting devices (LEDS), is also studied. It is concluded that negative charge is transferred from the aluminum to the polymer, resulting in a thin layer of oxidized aluminum and a more reduced form of the polymer at the interface. In studying polymer-polymer interfaces, it is proposed that NSPAN protonates a pyridine containing polymer at an interface which is also found in some LEDs. This is proposed to be responsible for color variation found in some LEDs. A model system was studied, and protonation at the polymer-polymer interface was directly observed, supporting the earlier proposals. Polymer-polymer interfaces found in SCALE devices, which are LEDs made with three polymer layers, are studied by UPS to determine the band structure of these devices. It is concluded that the EB layers decrease the hole barrier and increase the electron barrier, which leads to better charge balance and a better device. The EB

  19. Use of hybrid composite particles prepared using alkoxysilane-functionalized amphiphilic polymer precursors for simultaneous removal of various pollutants from water.

    PubMed

    Cho, Seulki; Kim, Nahae; Lee, Soonjae; Lee, Hoseok; Lee, Sang-Hyup; Kim, Juyoung; Choi, Jae-Woo

    2016-08-01

    In this study, we present new inorganic-organic hybrid particles and their possible application as an adsorbent for simultaneous removal of hydrophobic and hydrophilic pollutants from water. These hybrid particles were prepared using tailor-made alkoxysilane-functionalized amphiphilic polymer precursors (M-APAS), which have amphiphilic polymers and reactive alkoxysilane groups attached to the same backbone. Through a single conventional sol-gel process, the polymerization of M-APAS and the chemical conjugation of M-APAS onto silica nanoparticles was simultaneous, resulting in the formation of hybrid particles (M-APAS-SiO2) comprised of hyperbranch-like amphiphilic polymers bonded onto silica nanoparticles with a relatively high grafting efficiency. A test for the adsorption of water-soluble dye (organe-16) and water insoluble dye (solvent blue-35) onto the hybrid particles was performed to evaluate the possibility of adsorbing hydrophilic and hydrophobic compound within the same particle. The hybrid particle was also evaluated as an adsorbent for the removal of contaminated water containing various pollutants by wastewater treatment test. The hybrid particle could remove phenolic compounds from wastewater and the azo dye reactive orange-16 from aqueous solutions, and it was easily separated from the treated wastewater because of the different densities involved. These results demonstrate that the hybrid particles are a promising sorbent for hydrophilic and/or hydrophobic pollutants in water. PMID:27179430

  20. Utilization of polymer enclosed intermediate class arresters to improve the performance of modern power systems

    SciTech Connect

    Sakich, J.D.; Lenk, D.W. ); Koepfinger, J.L. )

    1992-07-01

    This paper introduces the first commercially available polymer enclosed intermediate class metal oxide surge arrester. It describes the unique construction of the design, including reduced size, increased flexibility, a collared seal on the polymer housing and an open webbed fiberglass-epoxy module which houses the metal oxide disc elements. Performance advantages are discussed. These include improved short term contamination performance of the insulator-like polymer design when compared to multi-unit porcelain housed designs. Data will show that polymer housed open-webbed fiberglass module construction extends the pressure relief capability beyond that of typical porcelain enclosed designs. The capability of the polymer enclosed design to withstand repeated pressure relief tests, simulating system reclose on a failed arrester, is also discussed. This paper discusses the circumstances at one utility which has considered utilizing polymer enclosed intermediate class arresters to effectively upgrade their system protection capabilities.

  1. Bistable electroactive polymers (BSEP): large-strain actuation of rigid polymers

    NASA Astrophysics Data System (ADS)

    Yu, Zhibin; Niu, Xiaofan; Brochu, Paul; Yuan, Wei; Li, Huafeng; Chen, Bin; Pei, Qibing

    2010-04-01

    Reversible, large-strain, bistable actuation has been a lasting puzzle in the pursuit of smart materials and structures. Conducting polymers are bistable, but the achievable strain is small. Large deformations have been achieved in dielectric elastomers at the expense of mechanical strength. The gel or gel-like soft polymers generally have elastic moduli around or less than 10 MPa. The deformed polymer relaxes to its original shape once the applied electric field is removed. We report new, bistable electroactive polymers (BSEP) that are capable of electrically actuated strains as high as 335% area strain. The BSEP could be useful for constructing rigid structures. The structures can support high mechanical loads, and be actuated to large-strain deformations. We will present one unique application of the BSEP for Braille displays that can be quickly refreshed and maintain the displayed contents without a bias voltage.

  2. Polymerization of Ethylene Oxide, Propylene Oxide, and Other Alkylene Oxides: Synthesis, Novel Polymer Architectures, and Bioconjugation.

    PubMed

    Herzberger, Jana; Niederer, Kerstin; Pohlit, Hannah; Seiwert, Jan; Worm, Matthias; Wurm, Frederik R; Frey, Holger

    2016-02-24

    The review summarizes current trends and developments in the polymerization of alkylene oxides in the last two decades since 1995, with a particular focus on the most important epoxide monomers ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO). Classical synthetic pathways, i.e., anionic polymerization, coordination polymerization, and cationic polymerization of epoxides (oxiranes), are briefly reviewed. The main focus of the review lies on more recent and in some cases metal-free methods for epoxide polymerization, i.e., the activated monomer strategy, the use of organocatalysts, such as N-heterocyclic carbenes (NHCs) and N-heterocyclic olefins (NHOs) as well as phosphazene bases. In addition, the commercially relevant double-metal cyanide (DMC) catalyst systems are discussed. Besides the synthetic progress, new types of multifunctional linear PEG (mf-PEG) and PPO structures accessible by copolymerization of EO or PO with functional epoxide comonomers are presented as well as complex branched, hyperbranched, and dendrimer like polyethers. Amphiphilic block copolymers based on PEO and PPO (Poloxamers and Pluronics) and advances in the area of PEGylation as the most important bioconjugation strategy are also summarized. With the ever growing toolbox for epoxide polymerization, a "polyether universe" may be envisaged that in its structural diversity parallels the immense variety of structural options available for polymers based on vinyl monomers with a purely carbon-based backbone. PMID:26713458

  3. Nanoporous polymer electrolyte

    SciTech Connect

    Elliott, Brian; Nguyen, Vinh

    2012-04-24

    A nanoporous polymer electrolyte and methods for making the polymer electrolyte are disclosed. The polymer electrolyte comprises a crosslinked self-assembly of a polymerizable salt surfactant, wherein the crosslinked self-assembly includes nanopores and wherein the crosslinked self-assembly has a conductivity of at least 1.0.times.10.sup.-6 S/cm at 25.degree. C. The method of making a polymer electrolyte comprises providing a polymerizable salt surfactant. The method further comprises crosslinking the polymerizable salt surfactant to form a nanoporous polymer electrolyte.

  4. Peptide–polymer ligands for a tandem WW-domain, an adaptive multivalent protein–protein interaction: lessons on the thermodynamic fitness of flexible ligands

    PubMed Central

    Koschek, Katharina; Durmaz, Vedat; Krylova, Oxana; Wieczorek, Marek; Gupta, Shilpi; Richter, Martin; Bujotzek, Alexander; Fischer, Christina; Haag, Rainer; Freund, Christian; Weber, Marcus

    2015-01-01

    Summary Three polymers, poly(N-(2-hydroxypropyl)methacrylamide) (pHPMA), hyperbranched polyglycerol (hPG), and dextran were investigated as carriers for multivalent ligands targeting the adaptive tandem WW-domain of formin-binding protein (FBP21). Polymer carriers were conjugated with 3–9 copies of the proline-rich decapeptide GPPPRGPPPR-NH2 (P1). Binding of the obtained peptide–polymer conjugates to the tandem WW-domain was investigated employing isothermal titration calorimetry (ITC) to determine the binding affinity, the enthalpic and entropic contributions to free binding energy, and the stoichiometry of binding for all peptide–polymer conjugates. Binding affinities of all multivalent ligands were in the µM range, strongly amplified compared to the monovalent ligand P1 with a K D > 1 mM. In addition, concise differences were observed, pHPMA and hPG carriers showed moderate affinity and bound 2.3–2.8 peptides per protein binding site resulting in the formation of aggregates. Dextran-based conjugates displayed affinities down to 1.2 µM, forming complexes with low stoichiometry, and no precipitation. Experimental results were compared with parameters obtained from molecular dynamics simulations in order to understand the observed differences between the three carrier materials. In summary, the more rigid and condensed peptide–polymer conjugates based on the dextran scaffold seem to be superior to induce multivalent binding and to increase affinity, while the more flexible and dendritic polymers, pHPMA and hPG are suitable to induce crosslinking upon binding. PMID:26124884

  5. Peptide-polymer ligands for a tandem WW-domain, an adaptive multivalent protein-protein interaction: lessons on the thermodynamic fitness of flexible ligands.

    PubMed

    Koschek, Katharina; Durmaz, Vedat; Krylova, Oxana; Wieczorek, Marek; Gupta, Shilpi; Richter, Martin; Bujotzek, Alexander; Fischer, Christina; Haag, Rainer; Freund, Christian; Weber, Marcus; Rademann, Jörg

    2015-01-01

    Three polymers, poly(N-(2-hydroxypropyl)methacrylamide) (pHPMA), hyperbranched polyglycerol (hPG), and dextran were investigated as carriers for multivalent ligands targeting the adaptive tandem WW-domain of formin-binding protein (FBP21). Polymer carriers were conjugated with 3-9 copies of the proline-rich decapeptide GPPPRGPPPR-NH2 (P1). Binding of the obtained peptide-polymer conjugates to the tandem WW-domain was investigated employing isothermal titration calorimetry (ITC) to determine the binding affinity, the enthalpic and entropic contributions to free binding energy, and the stoichiometry of binding for all peptide-polymer conjugates. Binding affinities of all multivalent ligands were in the µM range, strongly amplified compared to the monovalent ligand P1 with a K D > 1 mM. In addition, concise differences were observed, pHPMA and hPG carriers showed moderate affinity and bound 2.3-2.8 peptides per protein binding site resulting in the formation of aggregates. Dextran-based conjugates displayed affinities down to 1.2 µM, forming complexes with low stoichiometry, and no precipitation. Experimental results were compared with parameters obtained from molecular dynamics simulations in order to understand the observed differences between the three carrier materials. In summary, the more rigid and condensed peptide-polymer conjugates based on the dextran scaffold seem to be superior to induce multivalent binding and to increase affinity, while the more flexible and dendritic polymers, pHPMA and hPG are suitable to induce crosslinking upon binding. PMID:26124884

  6. Practitioner Perspectives on Foundational Capabilities

    PubMed Central

    Leider, Jonathon P.; Juliano, Chrissie; Castrucci, Brian C.; Beitsch, Leslie M.; Dilley, Abby; Nelson, Rachel; Kaiman, Sherry; Sprague, James B.

    2015-01-01

    Context: National efforts are underway to classify a minimum set of public health services that all jurisdictions throughout the United States should provide regardless of location. Such a set of basic programs would be supported by crosscutting services, known as the “foundational capabilities” (FCs). These FCs are assessment services, preparedness and disaster response, policy development, communications, community partnership, and organizational support activities. Objective: To ascertain familiarity with the term and concept of FCs and gather related perspectives from state and local public health practitioners. Design: In fall 2013, we interviewed 50 leaders from state and local health departments. We asked about familiarity with the term “foundational capabilities,” as well as the broader concept of FCs. We attempted to triangulate the utility of the FC concept by asking respondents about priority programs and services, about perceived unique contributions made by public health, and about prevalence and funding for the FCs. Setting: Telephone-based interviews. Participants: Fifty leaders of state and local health departments. Main Outcome Measures: Practitioner familiarity with and perspectives on the FCs, information about current funding streams for public health, and the likelihood of creating nationwide FCs that would be recognized and accepted by all jurisdictions. Results: Slightly more than half of the leaders interviewed said that they were familiar with the concept of FCs. In most cases, health departments had all of the capabilities to some degree, although operationalization varied. Few indicated that current funding levels were sufficient to support implementing a minimum level of FCs nationally. Conclusions: Respondents were not able to articulate the current or optimal levels of services for the various capabilities, nor the costs associated with them. Further research is needed to understand the role of FCs as part of the foundational

  7. The Capabilities of Space Stations

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Over the past two years the U.S. space station program has evolved to a three-phased international program, with the first phase consisting of the use of the U.S. Space Shuttle and the upgrading and use of the Russian Mir Space Station, and the second and third phases consisting of the assembly and use of the new International Space Station. Projected capabilities for research, and plans for utilization, have also evolved and it has been difficult for those not directly involved in the design and engineering of these space stations to learn and understand their technical details. The Committee on the Space Station of the National Research Council, with the concurrence of NASA, undertook to write this short report in order to provide concise and objective information on space stations and platforms -- with emphasis on the Mir Space Station and International Space Station -- and to supply a summary of the capabilities of previous, existing, and planned space stations. In keeping with the committee charter and with the task statement for this report, the committee has summarized the research capabilities of five major space platforms: the International Space Station, the Mir Space Station, the Space Shuttle (with a Spacelab or Spacehab module in its cargo bay), the Space Station Freedom (which was redesigned to become the International Space Station in 1993 and 1994), and Skylab. By providing the summary, together with brief descriptions of the platforms, the committee hopes to assist interested readers, including scientists and engineers, government officials, and the general public, in evaluating the utility of each system to meet perceived user needs.

  8. Polymer electroluminescent devices processed by inkjet printing: I. Polymer light-emitting logo

    NASA Astrophysics Data System (ADS)

    Bharathan, Jayesh; Yang, Yang

    1998-05-01

    Inkjet printing (IJP) technology is a popular technology for desktop publishing. Since some of the conducting (or conjugated) polymers are solution processable, IJP technology becomes an ideal method for printing polymer light-emitting diodes with high resolution. Unfortunately, the polymer film printed from an inkjet printer usually consists of pin-holes, and this intrinsic character makes it unsuitable for fabricating high quality polymer electronic devices, particularly for devices in the sandwich structure. In this letter, we submit a hybrid structure, which consists of an inkjet printed layer in conjunction with another uniform spin coated polymer layer, as an alternative to the regular inkjet printed structure. The uniform layer serves as a buffer layer to seal the pin-holes and the IJP layer is the layer consisting of the desired pattern, for example the red-green-blue dots for a multicolor display. To demonstrate, we applied this hybrid technology to fabricate efficient and large area polymer light-emitting logos. The use of this concept represents a whole new technology of fabricating polymer electronic devices with lateral patterning capability.

  9. GLAST GRB Observations and Capabilities

    NASA Technical Reports Server (NTRS)

    Meegan, Charles

    2008-01-01

    Gamma Ray Large Area Space Telescope (GLAST) is schedule to launch on May 16, 2008. GLAST consists of the Large Area Telescope (LAT), which will detect gamma rays above 20 MeV with unprecedented sensitivity, and the GLAST Burst Monitor (GBM), which will provide all-sky monitoring of GRBS in the 10 kev to 30 MeV range. Predicted GRB capabilities of GLAST will be described. The on-orbit performance of the instruments and preliminary GRB observations will be presented.

  10. ITER EDA design confinement capability

    NASA Astrophysics Data System (ADS)

    Uckan, N. A.

    Major device parameters for ITER-EDA and CDA are given in this paper. Ignition capability of the EDA (and CDA) operational scenarios is evaluated using both the 1 1/2-D time-dependent transport simulations and 0-D global models under different confinement ((chi((gradient)(T)(sub e)(sub crit)), empirical global energy confinement scalings, chi(empirical), etc.) assumptions. Results from some of these transport simulations and confinement assessments are summarized in and compared with the ITER CDA results.

  11. Predictive Capability Maturity Model (PCMM).

    SciTech Connect

    Swiler, Laura Painton; Knupp, Patrick Michael; Urbina, Angel

    2010-10-01

    Predictive Capability Maturity Model (PCMM) is a communication tool that must include a dicussion of the supporting evidence. PCMM is a tool for managing risk in the use of modeling and simulation. PCMM is in the service of organizing evidence to help tell the modeling and simulation (M&S) story. PCMM table describes what activities within each element are undertaken at each of the levels of maturity. Target levels of maturity can be established based on the intended application. The assessment is to inform what level has been achieved compared to the desired level, to help prioritize the VU activities & to allocate resources.

  12. Determining your organization's 'risk capability'.

    PubMed

    Hannah, Bill; Hancock, Melinda

    2014-05-01

    An assessment of a provider's level of risk capability should focus on three key elements: Business intelligence, including sophisticated analytical models that can offer insight into the expected cost and quality of care for a given population. Clinical enterprise maturity, marked by the ability to improve health outcomes and to manage utilization and costs to drive change. Revenue transformation, emphasizing the need for a revenue cycle platform that allows for risk acceptance and management and that provides incentives for performance against defined objectives. PMID:24851456

  13. Drop Tower and Aircraft Capabilities

    NASA Technical Reports Server (NTRS)

    Urban, David L.

    2015-01-01

    This presentation is a brief introduction to existing capabilities in drop towers and low-gravity aircraft that will be presented as part of a Symposium: Microgravity Platforms Other Than the ISS, From Users to Suppliers which will be a half day program to bring together the international community of gravity-dependent scientists, program officials and technologists with the suppliers of low gravity platforms (current and future) to focus on the future requirements and use of platforms other than the International Space Station (ISS).

  14. In vitro and in vivo evaluation of intravesical docetaxel loaded hydrophobically derivatized hyperbranched polyglycerols in an orthotopic model of bladder cancer.

    PubMed

    Mugabe, Clement; Matsui, Yoshiyuki; So, Alan I; Gleave, Martin E; Heller, Markus; Zeisser-Labouèbe, Magali; Heller, Lindsay; Chafeeva, Irina; Brooks, Donald E; Burt, Helen M

    2011-04-11

    The objective of this study was to evaluate the tolerability, to establish a dosing regimen, and to evaluate the efficacy of intravesical docetaxel (DTX) formulations in a mouse model of bladder cancer. DTX in commercial formulation (Taxotere, DTX in Tween 80) or loaded in hyperbranched polyglycerols (HPGs) was evaluated. The synthesis and characterization of HPGs with hydrophobic cores and derivatized with methoxy poly(ethylene glycol) in the shell and further functionalized with amine groups (HPG-C(8/10)-MePEG and HPG-C(8/10)-MePEG-NH(2)) is described. Intravesical DTX in either commercial or HPGs formulations (up to 1.0 mg/mL) was instilled in mice with orthotopic bladder cancer xenografts and was well tolerated with no apparent signs of local or systemic toxicities. Furthermore, a single dose of intravesical DTX (0.5 mg/mL) loaded in HPGs was significantly more effective in reducing the tumor growth in an orthotopic model of bladder cancer than the commercial formulation of Taxotere. In addition, DTX-loaded HPG-C(8/10)-MePEG-NH(2) was found to be more effective at lower instillation dose than DTX (0.2 mg/mL)-loaded HPG-C(8/10)-MePEG. Overall, our data show promising antitumor efficacy and safety in a recently validated orthotopic model of bladder cancer. Further research is warranted to evaluate its safety and efficacy in early phase clinical trials in patients refractory to standard intravesical therapy. PMID:21355626

  15. Highly Selective and Sensitive Electrochemiluminescence Biosensor for p53 DNA Sequence Based on Nicking Endonuclease Assisted Target Recycling and Hyperbranched Rolling Circle Amplification.

    PubMed

    Yang, Linlin; Tao, Yingzhou; Yue, Guiyin; Li, Ruibao; Qiu, Bin; Guo, Longhua; Lin, Zhenyu; Yang, Huang-Hao

    2016-05-17

    An ultrasensitive and specific electrochemiluminescence (ECL) biosensor has been designed for the p53 DNA sequence, which is based on cascade signal amplification of nicking endonuclease assisted target recycling and hyperbranched rolling circle amplification (HRCA). First of all, biotin modified hairpin capture DNA (HP) probe was immobilized on the surface of streptavidin magnespheres paramagnetic particles (PMPs). Target DNA hybridized with the loop portion of the HP probe, therefore unfolding HP to form a double-stranded DNA (dsDNA) containing the specific nicking site of the nicking endonuclease. Then, the nicking endonuclease recognized the specific nicking site and cleaved the HP into two pieces, liberating target DNA and the complementary sequence piece for the padlock probe. The intact target DNA would initiate the next cycle of hybridization and cleavage, thereby releasing multiple complementary sequences for the padlock probes. The liberated complementary sequences hybridized with the padlock probes, subsequently inducing the HRCA reaction and generating numerous dsDNA segments. Herein, Ru(phen)3(2+) was embedded into dsDNA and worked as ECL signal reporter. The reaction products were eventually pretreated by dialysis tube with the cutoff membrane to remove the residual Ru(phen)3(2+) in the solution for the following ECL measurements. Using this cascade amplification strategy, an ultrasensitive p53 DNA sequence detection method was developed with a wide linear range from 0.05 to 100 fM and a low detection limit of 0.02 fM. Moreover, this cascade amplified ECL biosensor had specific recognition capacity for noncomplementary and single- and double-base mismatched DNA. The proposed ECL biosensor might have a great potential in biomedical research and clinic analysis. PMID:27086663

  16. Multi-modal magnetic resonance imaging and histology of vascular function in xenografts using macromolecular contrast agent hyperbranched polyglycerol (HPG-GdF).

    PubMed

    Baker, Jennifer H E; McPhee, Kelly C; Moosvi, Firas; Saatchi, Katayoun; Häfeli, Urs O; Minchinton, Andrew I; Reinsberg, Stefan A

    2016-01-01

    Macromolecular gadolinium (Gd)-based contrast agents are in development as blood pool markers for MRI. HPG-GdF is a 583 kDa hyperbranched polyglycerol doubly tagged with Gd and Alexa 647 nm dye, making it both MR and histologically visible. In this study we examined the location of HPG-GdF in whole-tumor xenograft sections matched to in vivo DCE-MR images of both HPG-GdF and Gadovist. Despite its large size, we have shown that HPG-GdF extravasates from some tumor vessels and accumulates over time, but does not distribute beyond a few cell diameters from vessels. Fractional plasma volume (fPV) and apparent permeability-surface area product (aPS) parameters were derived from the MR concentration-time curves of HPG-GdF. Non-viable necrotic tumor tissue was excluded from the analysis by applying a novel bolus arrival time (BAT) algorithm to all voxels. aPS derived from HPG-GdF was the only MR parameter to identify a difference in vascular function between HCT116 and HT29 colorectal tumors. This study is the first to relate low and high molecular weight contrast agents with matched whole-tumor histological sections. These detailed comparisons identified tumor regions that appear distinct from each other using the HPG-GdF biomarkers related to perfusion and vessel leakiness, while Gadovist-imaged parameter measures in the same regions were unable to detect variation in vascular function. We have established HPG-GdF as a biocompatible multi-modal high molecular weight contrast agent with application for examining vascular function in both MR and histological modalities. PMID:26268906

  17. High performance polymer development

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M.

    1991-01-01

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

  18. CONFORMATIONAL PROPERTIES AND ENTROPIC PARTITIONING OF TOPOLOGICALLY COMPLEX POLYMERS UNDER CONFINEMENT - Final Report

    SciTech Connect

    Escobedo, Fernando A.

    2005-03-24

    The effect of molecular topology (e.g., branch and loop structures) on the solution properties of polymers is subtle and not well characterized. Because the conformational entropy of a polymer depends on its topology, many properties are affected by it such as its size and shape, mobility, bulk-to-pore partitioning, adsorption strength on surfaces, and depletion-induced forces on colloidal surfaces. We have systematically studied the effect of molecular topology on the structure and entropic partitioning of linear, branched, hyper-branched, cyclic, and hyper-cyclic polymers in a bulk solution and in pores. Ours is the first simulation study aimed at characterizing the conformational properties of hyper-cyclic molecules. Key findings: Our results show how differences in molecular architecture can be used to partition polymers in a porous media e.g., a highly branched polymer tends to be depleted in narrow pores (smaller than the coil size) relative to a less branched chain of equal molecular weight, but this trend is reversed in wide pores. It was also found that intra-molecular crosslinking (associated with cyclic structures) is an effective way to tune the conformational entropy of a polymer; the more crosslinks a molecule has, the smaller its conformational entropy, and the easier it is to adsorb it onto attractive pore walls. Intra-crosslinked chains are thus more effective steric stabilizer of colloid particles than linear chains (which are better depleting agents). Simulations were also used to investigate the mechanism of entropic trapping for model linear and branched DNA molecules as they go from a deep channel to a shallow channel driven by an electric field. In such a system, a molecule whose radius of gyration is larger than the gap of the shallow channel tends to get temporarily trapped at its entrance. Our results show that at moderate and strong fields, longer chains escape faster than shorter ones because, in the absence of significant differences in

  19. The "universal polymer backbone" concept

    NASA Astrophysics Data System (ADS)

    Pollino, Joel Matthew

    This thesis begins with a brief analysis of the synthetic methodologies utilized in polymer science. A conclusion is drawn inferring that upper limits in molecular design are inevitable, arising as a direct consequence of the predominance of covalent strategies in the field. To address these concerns, the 'universal polymer backbone' (UPB) concept has been hypothesized. A UPB has been defined as any copolymer, side-chain functionalized with multiple recognition elements that are individually capable of forming strong, directional, and reversible non-covalent bonds. Non-covalent functionalization of these scaffolds can lead to the formation of a multitude of new polymer structures, each stemming from a single parent or 'universal polymer backbone'. To prepare such a UPB, isomerically pure exo-norbornene esters containing either a PdII SCS pincer complex or a diaminopyridine residue were synthesized, polymerized, and copolymerized via ROMP. All polymerizations were living under mild reaction conditions. Kinetic studies showed that the kp values are highly dependent upon the isomeric purity but completely independent of the terminal recognition units. Non-covalent functionalization of these copolymers was accomplished via (1) directed self-assembly, (2) multi-step self-assembly , and (3) one-step orthogonal self-assembly. This system shows complete specificity of each recognition motif for its complementary unit with no observable changes in the association constant upon functionalization. To explore potential applications of this UPB concept, random terpolymers possessing high concentrations of pendant alkyl chains and small amounts of recognition units were synthesized. Non-covalent crosslinking using a directed functionalization strategy resulted in dramatic increases in solution viscosities for metal crosslinked polymers with only minor changes in viscosity for hydrogen bonding motifs. The crosslinked materials were further functionalized via self-assembly by

  20. 'Smart' polymers in biotechnology and medicine

    NASA Astrophysics Data System (ADS)

    Galaev, Igor Yu

    1995-05-01

    'Smart' water-soluble polymers and hydrogels are capable of responding reversibly to slight changes in the properties of the medium (pH, temperature, ionic strength, the presence of certain substances, illumination, electric field), the response of the system being readily seen with the naked eye (the formation of a new phase in a hitherto homogeneous solution, sudden swelling or contraction of the hydrogel). The properties of such polymers and hydrogels are examined. The use of 'smart' polymers and hydrogels for the concentration of protein solutions and the dehydration of suspensions, for the creation of membranes with a controllable permeability, for the isolation and purification of biomolecules, for the immobilisation of biocatalysts, and for the creation of sensor systems and systems for the controlled release of medicinal drugs is discussed. The bibliography includes 261 references.

  1. Two Dimensional Polymer That Generates Nitric Oxide.

    DOEpatents

    McDonald, William F.; Koren, Amy B.

    2005-10-04

    A polymeric composition that generates nitric oxide and a process for rendering the surface of a substrate nonthrombogenic by applying a coating of the polymeric composition to the substrate are disclosed. The composition comprises: (1) a crosslinked chemical combination of (i) a polymer having amino group-containing side chains along a backbone forming the polymer, and (ii) a crosslinking agent containing functional groups capable of reacting with the amino groups; and (2) a plurality of nitric oxide generating functional groups associated with the crosslinked chemical combination. Once exposed to a physiological environment, the coating generates nitric oxide thereby inhibiting platelet aggregation. In one embodiment, the nitric oxide generating functional groups are provided by a nitrated compound (e.g., nitrocellulose) imbedded in the polymeric composition. In another embodiment, the nitric oxide generating functional groups comprise N2O2- groups covalently bonded to amino groups on the polymer.

  2. Polymer research at NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    St.clair, T. L.; Johnston, N. J.

    1982-01-01

    Polymer synthesis programs involve the development of Novel thermoplastics, pseudothermoplastics, and thermosets. These systems are prepared to elucidate structure-property relationships involving thermal capabilities, toughness, processability and environmental stability. Easily processable polyimides, solvent-resistant polysulfones and polyphenylquinoxalines, and tougher high and intermediate temperature polymers were developed. Characterization efforts included high pressure liquid chromatography methodology, the development of toughness tests for fiber reinforced composites, a study of electrical properties of metal ion filled polyimides, and a study of the mutagenicity of aromatic diamines. Also the mechanism of cure/degradation of experimental polymers was studied by rheology, mechanical behavior, separation techniques and spectroscopy. The degradative crosslinking of alkyl-containing polyimides, the separation and identification of crosslinked phenylquinoxalines, the rheological behavior of hot-melt polyimides, and the elucidation of the cure of norbornene endcapped imides were also studied.

  3. Polymer Energy Rechargeable System (PERS) Development Program

    NASA Technical Reports Server (NTRS)

    Baldwin, Richard S.; Manzo, Michelle A.; Dalton, Penni J.; Marsh, Richard A.; Surampudi, Rao

    2001-01-01

    The National Aeronautics and Space Administration (NASA) and the Air Force Research Laboratory (AFRL) have recently established a collaborative effort to support the development of polymer-based, lithium-based cell chemistries and battery technologies to address the next generation of aerospace applications and mission needs. The overall objective of this development program, which is referred to as PERS, Polymer Energy Rechargeable System, is to establish a world-class technology capability and U.S. leadership in polymer-based battery technology for aerospace applications. Programmatically, the PERS initiative will exploit both interagency collaborations to address common technology and engineering issues and the active participation of academia and private industry. The initial program phases will focus on R&D activities to address the critical technical issues and challenges at the cell level.

  4. Cyberinfrastructure for Rapid Prototyping Capability

    NASA Astrophysics Data System (ADS)

    Haupt, T. A.; Kalyanasundaram, A.; Zhuk, I.; Goli, V.

    2007-12-01

    The overall goal of the NASA Rapid Prototyping Capability is to speed the evaluation of potential uses of NASA research products and technologies to improve future operational systems by reducing the time to access, configure, and assess the effectiveness of NASA products and technologies. The infrastructure to support the RPC is thus expected to provide the capability to rapidly evaluate innovative methods of linking science observations. The RPC infrastructure supports two major categories of experiments (and subsequent analysis): comparing results of a particular model as fed with data coming from different sources, and comparing different models using the data coming from the same source. In spite of being conceptually simple, two use cases in fact entail a significant technical challenge. Enabling RPC experiments requires thus a radical simplification of access to both actual and simulated data, as well as tools for data pre- and post-processing. The tools must be interoperable, allowing the user to create computational workflows with the data seamlessly transferred as needed, including third-party transfers to high-performance computing platforms. In addition, the provenance of the data must be preserved in order to document results of different what-if scenarios and to enable collaboration and data sharing between users. The functionality of the RPC splits into several independent modules such as interactive Web site, data server, tool's interfaces, or monitoring service. Each such module is implemented as an independent portlet. The RPC Portal aggregates the different contents provided by the portlets into a single interface employing a popular GridSphere portlet container. The RPC data access is based on Unidata's THREDDS Data server (TDS) extended to support, among others, interactive creation of containers for new data collections and uploading new data sets, downloading the data either to the user desktop or transferring it to a remote location using

  5. Satellite Servicing Capabilities Office Testing

    NASA Technical Reports Server (NTRS)

    Sanders, Sean

    2015-01-01

    While at the KSC, I was given the opportunity of assisting the Satellite Servicing Capabilities Office (SSCO) specifically the Propellant Transfer System (PTS) lead by my mentor, Brian Nufer. While waiting to test different components in the PTS, I was able to assist with testing for the Hose Management Assembly (HMA) and was able to work on a simulation in Labview. For the HMA, I was able to help with testing of a coating as well as to help test the durability of the pinch rollers in space. In Labview, I experimented with building a simulation for the PTS, to show where fluids and gases were flowing depending on which valves in the PTS were opened. Not all of the integrated parts required assembly level testing, which allowed me to test these parts individually by myself and document the results. I was also able to volunteer to assist project NEO, allowing me to gain some knowledge of cryogenic fluid systems.

  6. The polarimetric capabilities of NICMOS

    NASA Technical Reports Server (NTRS)

    Hines, D. C.; Schmidt, G. D.; Lytle, Dyer

    1997-01-01

    The polarimetric capabilities of Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) are demonstrated from data obtained during the Early Release Observations of IRC+10216 and CRL 2688 (the Egg Nebula). Preflight Thermal Vacuum tests revealed that each polarizer has a unique polarizing efficiency, and that the position angle offsets differ from the nominal positions of O deg, 120 deg and 240 deg. Therefore an algorithm different from that of an ideal polarizer is required for proper reduction of astronomical polarimetry data. We discuss this new algorithm and the results of its application to NICMOS data. We also present preliminary estimates of the Instrumental Polarization, the sensitivity of the grisms to polarized light, and the accuracy of NICMOS imaging polarimetry for faint and low polarization objects. Finally, we suggest strategies for maximizing the success of NICMOS polarimetry observations.

  7. Integrated Urban Dispersion Modeling Capability

    SciTech Connect

    Kosovic, B; Chan, S T

    2003-11-03

    Numerical simulations represent a unique predictive tool for developing a detailed understanding of three-dimensional flow fields and associated concentration distributions from releases in complex urban settings (Britter and Hanna 2003). The accurate and timely prediction of the atmospheric dispersion of hazardous materials in densely populated urban areas is a critical homeland and national security need for emergency preparedness, risk assessment, and vulnerability studies. The main challenges in high-fidelity numerical modeling of urban dispersion are the accurate prediction of peak concentrations, spatial extent and temporal evolution of harmful levels of hazardous materials, and the incorporation of detailed structural geometries. Current computational tools do not include all the necessary elements to accurately represent hazardous release events in complex urban settings embedded in high-resolution terrain. Nor do they possess the computational efficiency required for many emergency response and event reconstruction applications. We are developing a new integrated urban dispersion modeling capability, able to efficiently predict dispersion in diverse urban environments for a wide range of atmospheric conditions, temporal and spatial scales, and release event scenarios. This new computational fluid dynamics capability includes adaptive mesh refinement and it can simultaneously resolve individual buildings and high-resolution terrain (including important vegetative and land-use features), treat complex building and structural geometries (e.g., stadiums, arenas, subways, airplane interiors), and cope with the full range of atmospheric conditions (e.g. stability). We are developing approaches for seamless coupling with mesoscale numerical weather prediction models to provide realistic forcing of the urban-scale model, which is critical to its performance in real-world conditions.

  8. Vacuum deposited polymer/metal films for optical applications

    SciTech Connect

    Affinito, J.D.; Martin, P.M.; Gross, M.E.; Coronado, C.; Greenwell, E.

    1995-04-01

    Vacuum deposited Polymer/Silver/Polymer reflectors and Tantalum/Polymer/Aluminum Fabry-Perot interference filters were fabricated in a vacuun web coating operation on polyester substrates with a new, high speed deposition process. Reflectivities were measured in the wavelength range from 0.3 to 0.8{mu}m. This new vacuum processing technique has been shown to be capable of deposition line speeds in excess of 500 linear meters/minute. Central to this technique is a new position process for the high rate deposition of polymer films. This polymer process involves the flash evaporation of an acrylic monomer onto a moving substrate. The monomer is subsequently cured by an electron beam or ultraviolet light. This high speed polymer film deposition process has been named the PML process -- for Polymer Multi-Layer. Also, vacuum deposited, index matched, polymer/CaF{sub 2} composites were fabricated from monomer slurries that were subsequently cured with LTV light. This second technique is called the Liquid Multi-Layer (or LML) process. Each of these polymer processes is compatible with each other and with conventional vacuum deposition processes such as sputtering or evaporation.

  9. LANL capabilities towards bioenergy and biofuels programs

    SciTech Connect

    Olivares, Jose A; Park, Min S; Unkefer, Clifford J; Bradbury, Andrew M; Waldo, Geoffrey S

    2009-01-01

    LANL invented technology for increasing growth and productivity of photosysnthetic organisms, including algae and higher plants. The technology has been extensively tested at the greenhouse and field scale for crop plants. Initial bioreactor testing of its efficacy on algal growth has shown promising results. It increases algal growth rates even under optimwn nutrient supply and careful pH control with CO{sub 2} continuously available. The technology uses a small organic molecule, applied to the plant surfaces or added to the algal growth medium. CO{sub 2} concentration is necessary to optimize algal production in either ponds or reactors. LANL has successfully designed, built and demonstrated an effective, efficient technology using DOE funding. Such a system would be very valuable for capitalizing on local inexpensive sources of CO{sub 2} for algal production operations. Furthermore, our protein engineering team has a concept to produce highly stable carbonic anhydyrase (CA) enzyme, which could be very useful to assure maximum utilization of the CO{sub 2} supply. Stable CA could be used either imnlobilized on solid supports or engineered into the algal strain. The current technologies for harvesting the algae and obtaining the lipids do not meet the needs for rapid, low cost separations for high volumes of material. LANL has obtained proof of concept for the high volume flowing stream concentration of algae, algal lysis and separation of the lipid, protein and water fractions, using acoustic platforms. This capability is targeted toward developing biosynthetics, chiral syntheses, high throughput protein expression and purification, organic chemistry, recognition ligands, and stable isotopes geared toward Bioenergy applications. Areas of expertise include stable isotope chemistry, biomaterials, polymers, biopolymers, organocatalysis, advanced characterization methods, and chemistry of model compounds. The ultimate realization of the ability to design and

  10. Molecules with enhanced electronic polarizabilities based on defect-like states in conjugated polymers

    NASA Technical Reports Server (NTRS)

    Beratan, David N. (Inventor)

    1991-01-01

    Highly conjugated organic polymers typically have large non-resonant electronic susceptibilities, which give the molecules unusual optical properties. To enhance these properties, defects are introduced into the polymer chain. Examples include light doping of the conjugated polymer and synthesis, conjugated polymers which incorporate either electron donating or accepting groups, and conjugated polymers which contain a photoexcitable species capable of reversibly transferring its electron to an acceptor. Such defects in the chain permit enhancement of the second hyperpolarizability by at least an order of magnitude.

  11. Amartya Sen's Capability Approach and Education

    ERIC Educational Resources Information Center

    Walker, Melanie

    2005-01-01

    The human capabilities approach developed by the economist Amartya Sen links development, quality of life and freedom. This article explores the key ideas in the capability approach of: capability, functioning, agency, human diversity and public participation in generating valued capabilities. It then considers how these ideas relate specifically…

  12. Frontiers in polymer chemistry.

    PubMed

    Schlüter, A Dieter

    2013-01-01

    The article shows how the initial concept of Staudinger on linear macromolecules was expanded topologically by increasing the cross-section diameter of polymer chains and by introducing sheet polymers with planar rather than the commonly known linear repeat units. The two concrete projects addressed are the synthesis of dendronized and of two-dimensional polymers. It is explained how these novel macromolecules were achieved and which obstacles had to be overcome but also where these frontiers in polymer chemistry might lead to new insights in polymer science in general and novel applications in particular. The article also provides insights into analytical issues because both target macromolecules are in an extraordinarily high molar mass range and contrast/sensitivity issues can turn rather serious in particular for the two-dimensional polymers. PMID:24388233

  13. 3D Printing of Biocompatible Supramolecular Polymers and their Composites.

    PubMed

    Hart, Lewis R; Li, Siwei; Sturgess, Craig; Wildman, Ricky; Jones, Julian R; Hayes, Wayne

    2016-02-10

    A series of polymers capable of self-assembling into infinite networks via supramolecular interactions have been designed, synthesized, and characterized for use in 3D printing applications. The biocompatible polymers and their composites with silica nanoparticles were successfully utilized to deposit both simple cubic structures, as well as a more complex twisted pyramidal feature. The polymers were found to be not toxic to a chondrogenic cell line, according to ISO 10993-5 and 10993-12 standard tests and the cells attached to the supramolecular polymers as demonstrated by confocal microscopy. Silica nanoparticles were then dispersed within the polymer matrix, yielding a composite material which was optimized for inkjet printing. The hybrid material showed promise in preliminary tests to facilitate the 3D deposition of a more complex structure. PMID:26766139

  14. High Performance Polymers

    NASA Technical Reports Server (NTRS)

    Venumbaka, Sreenivasulu R.; Cassidy, Patrick E.

    2003-01-01

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

  15. Polymer concrete patching manual

    NASA Astrophysics Data System (ADS)

    Fontana, J. J.; Bartholomew, J.

    1982-06-01

    The practicality of using polymer concrete to repair deteriorated portland cement concrete bridge decks and pavements was demonstrated. This manual outlines the procedures for using polymer concrete as a rapid patching material to repair deteriorated concrete. The process technology, materials, equipment, and safety provisions used in manufacturing and placing polymer concrete are discussed. Potential users are informed of the various steps necessary to insure successful field applications of the material.

  16. Thermally conductive polymers

    NASA Technical Reports Server (NTRS)

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

    1971-01-01

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

  17. The design and synthesis of electroactive and magnetic polymers

    SciTech Connect

    Rock, M.M. Jr.

    1993-01-01

    Ring-opening metathesis polymerization (ROMP) remains a valuable tool in polymer synthesis because it affords structurally well-defined, functionalized materials with highly unsaturated polymer backbones. The power and flexibility of organic and polymer chemistry are used here to create fully conjugated, electroactive organic polymers. A series of electroactive poly(norbornadienebenzoquinone-imine) and poly(norbornadienebenzoquinone) polymers have been synthesized by the ring-opening metathesis polymerization (ROMP) of functionalized bicyclo[2.2.1]hepta-2,5-dienes using alkylidene metathesis catalysts. Incorporation of these quinone and imine redox units into organic norbornadiene polymers generates highly reactive and conductive materials capable of charge storage and electrochromism. An improved precursor polymer route is described to polyparaphenylene (PPP) based upon the ring-opening metathesis polymerization (ROMP) chemistry of cis-di(3,4-dihydroxymethyl)cyclobutene dicarbonate. These precursor polybutenamers undergo a final conversion to insoluble polyparaphenylene (PPP) without destroying or disturbing the existing polymer structure. These polybutenamers are of great interest because they incorporate high degrees of acid, oxygen, and heteroatom functionality into a soluble 1,4-poly(butadiene) structure. Organic magnets offer new insights into the nature of magnetism and lead to the development of materials with unique optical, electrical, and magnetic properties. To test the Topological Coupling Model an organic-based ferromagnetic polymer was designed around the ring-opening metathesis polymerization (ROMP) of 3-diphenylmethylenecyclobutene. Doping, the generation of charged species along the polymer, generates a radical spin (1,2) on every monomer unit in the polymer chain, resulting in a fully conjugated polybutenamer polymer. Oxidative doping of this material evokes ferromagnetic couplings among unpaired spins in the material.

  18. Predictive aging of polymers

    NASA Technical Reports Server (NTRS)

    Cuddihy, Edward F. (Inventor); Willis, Paul B. (Inventor)

    1990-01-01

    A method of predicting aging of polymers operates by heating a polymer in the outdoors to an elevated temperature until a change of property is induced. The test is conducted at a plurality of temperatures to establish a linear Arrhenius plot which is extrapolated to predict the induction period for failure of the polymer at ambient temperature. An Outdoor Photo Thermal Aging Reactor (OPTAR) is also described including a heatable platen for receiving a sheet of polymer, means to heat the platen and switching means such as a photoelectric switch for turning off the heater during dark periods.

  19. Predictive aging of polymers

    NASA Technical Reports Server (NTRS)

    Cuddihy, Edward F. (Inventor); Willis, Paul B. (Inventor)

    1989-01-01

    A method of predicting aging of polymers operates by heating a polymer in the outdoors to an elevated temperature until a change of property is induced. The test is conducted at a plurality of temperatures to establish a linear Arrhenius plot which is extrapolated to predict the induction period for failure of the polymer at ambient temperature. An Outdoor Photo Thermal Aging Reactor (OPTAR) is also described including a heatable platen for receiving a sheet of polymer, means to heat the platen, and switching means such as a photoelectric switch for turning off the heater during dark periods.

  20. Polymers for engineering applications

    SciTech Connect

    Seymour, R.B.

    1987-01-01

    This book provides an introduction to the world of engineering plastics. It discusses the polymers, their properties strengths and limitations. There are 11 chapters, organized so that each chapter builds on the knowledge of the previous material. Coverage includes important polymer concepts, such as molecular structure, bonding, morphology and molecular weight, and polymer properties, such as thermal expansion, thermal transition, electrical properties and viscoelasticity. Details are provided on methods of processing fabrication and on specific families of polymers. The general-purpose polymers are discussed, such as natural and synthetic rubbers, rayon, acrylic and alkyd coatings, polyethylene, polystyrene and polyvinyl chloride (PVC). There's information on high-performance polymers - fibers, elastomers, and coatings. A thorough explanation of the characteristics and qualities of nylons, polyesters, polyimides, neoprene, silicones, polyurethanes and other polymers is given in the same section. Functional polymers with special properties, such as photoconductivity, electric conductivity, piezoelectricity, light sensitivity, and ion exchange; and polymers that are superior to general-purpose plastics, such as ABS, filled polypropylene, and glass-reinforced plastics, are also covered.

  1. Antioxidant Stabilisation of Polymers

    NASA Astrophysics Data System (ADS)

    Shlyapnikov, Yurii A.

    1981-06-01

    Physicochemical aspects of the stabilisation of polymers are discussed. Attention is paid mainly to the aging and stabilisation of polymers under processing conditions. Topics considered are the kinetics and mechanism of the high-temperature oxidation of polymers, critical phenomena in the inhibited oxidation of polymers, the theory of synergism and antagonism among antioxidants, the reasons for differences in efficiency of antioxidants, and certain aspects of the relation between the efficiency of antioxidants and their molecular structure. A list of 132 references is included.

  2. Analyses of viscoelastic solid polymers undergoing degradation

    NASA Astrophysics Data System (ADS)

    Davoodi, Bentolhoda; Muliana, Anastasia; Tscharnuter, Daniel; Pinter, Gerald

    2015-08-01

    In this paper we study the three-dimensional response of isotropic viscoelastic solid-like polymers undergoing degradation due to mechanical stimuli. A single integral model is used to describe the time-dependent behaviors of polymers under general loading histories. The degradation is associated to excessive deformations in the polymers as strains continuously increase when the mechanical stimuli are prescribed, and therefore we consider a degradation threshold in terms of strains. The degradation part of the deformations is unrecoverable, and upon removal of the prescribed external stimuli, the accumulation of the degradation strains lead to residual strains. We also systematically present material parameter characterization from available experimental data under various loading histories, i.e., ramp loading with different constant rates, creep-recovery under different stresses, and relaxation under several strains. We analyze viscoelastic-degradation response of two polymers, namely polyethylene and polyoxymethylene under uniaxial tensile tests. Longer duration of loading can lead to increase in the degradation of materials due to the substantial increase in the deformations. The single integral model is capable in predicting the time-dependent responses of the polymers under various loading histories and capturing the recovery and residual strains at different stages of degradations.

  3. Ferroelectric Polymer Composite with Enhanced Breakdown Strength

    NASA Astrophysics Data System (ADS)

    Han, Kuo; Gadinski, Matthew; Wang, Qing

    2013-03-01

    Numerous efforts have been made in the past decades to improve the energy storage capability of dielectric capacitors by incorporating ceramic addictives into polymers. Ferroelectric polymers have been particularly interesting as matrix for dielectric composites because of their highest dielectric permittivity and energy density. However, most polymer composites suffer from significantly reduced breakdown strength, which compromises the potential gain in energy density. In this work, various metallic alkoxide were introduced into the functionalized ferroelectric poly(vinylidene fluoride-co- chlorotrifluoroethylene), P(VDF-CTFE), via covalent bonding. The composite with the optimized composition exhibited the Weibull statistical breakdown strength of 504.8 MV/m, 67.6 % higher than the pristine polymer. The enhanced breakdown strength was mainly ascribed to the cross-linking and the formation of deep traps, which effectively reduced the conduction and further lowered the energy loss. Additionally, the homogeneous dispersion of the inorganic phase and the small contrast in permittivity between the polymer and amorphous oxides also contribute to the improved dielectric strength. The dielectric spectra of the composites have been recorded at varied temperatures and frequencies, which revealed the presence of the interfacial polarization layer in the composites.

  4. Solar mechanics thermal response capabilities.

    SciTech Connect

    Dobranich, Dean D.

    2009-07-01

    In many applications, the thermal response of structures exposed to solar heat loads is of interest. Solar mechanics governing equations were developed and integrated with the Calore thermal response code via user subroutines to provide this computational simulation capability. Solar heat loads are estimated based on the latitude and day of the year. Vector algebra is used to determine the solar loading on each face of a finite element model based on its orientation relative to the sun as the earth rotates. Atmospheric attenuation is accounted for as the optical path length varies from sunrise to sunset. Both direct and diffuse components of solar flux are calculated. In addition, shadowing of structures by other structures can be accounted for. User subroutines were also developed to provide convective and radiative boundary conditions for the diurnal variations in air temperature and effective sky temperature. These temperature boundary conditions are based on available local weather data and depend on latitude and day of the year, consistent with the solar mechanics formulation. These user subroutines, coupled with the Calore three-dimensional thermal response code, provide a complete package for addressing complex thermal problems involving solar heating. The governing equations are documented in sufficient detail to facilitate implementation into other heat transfer codes. Suggestions for improvements to the approach are offered.

  5. NASA Dryden's UAS Service Capabilities

    NASA Technical Reports Server (NTRS)

    Bauer, Jeff

    2007-01-01

    The vision of NASA s Dryden Flight Research Center is to "fly what others only imagine." Its mission is to advance technology and science through flight. Objectives supporting the mission include performing flight research and technology integration to revolutionize aviation and pioneer aerospace technology, validating space exploration concepts, conducting airborne remote sensing and science missions, and supporting operations of the Space Shuttle and the International Space Station. A significant focus of effort in recent years has been on Unmanned Aircraft Systems (UAS), both in support of the Airborne Science Program and as research vehicles to advance the state of the art in UAS. Additionally, the Center has used its piloted aircraft in support of UAS technology development. In order to facilitate greater access to the UAS expertise that exists at the Center, that expertise has been organized around three major capabilities. The first is access to high-altitude, long-endurance UAS. The second is the establishment of a test range for small UAS. The third is safety case assessment support.

  6. OPSAID improvements and capabilities report.

    SciTech Connect

    Halbgewachs, Ronald D.; Chavez, Adrian R.

    2011-08-01

    Process Control System (PCS) and Industrial Control System (ICS) security is critical to our national security. But there are a number of technological, economic, and educational impediments to PCS owners implementing effective security on their systems. Sandia National Laboratories has performed the research and development of the OPSAID (Open PCS Security Architecture for Interoperable Design), a project sponsored by the US Department of Energy Office of Electricity Delivery and Energy Reliability (DOE/OE), to address this issue. OPSAID is an open-source architecture for PCS/ICS security that provides a design basis for vendors to build add-on security devices for legacy systems, while providing a path forward for the development of inherently-secure PCS elements in the future. Using standardized hardware, a proof-of-concept prototype system was also developed. This report describes the improvements and capabilities that have been added to OPSAID since an initial report was released. Testing and validation of this architecture has been conducted in another project, Lemnos Interoperable Security Project, sponsored by DOE/OE and managed by the National Energy Technology Laboratory (NETL).

  7. JEM/SMILES observation capability

    NASA Astrophysics Data System (ADS)

    Kasai, Yasuko J.; Baron, Philippe; Ochiai, Satoshi; Mendrok, Jana; Urban, Joachim; Murtagh, Donal; Moller, Joakim; Manabe, Takeshi; Kikuchi, Kenichi; Nishibori, Toshiyuki

    2009-09-01

    A new generation of sub-millimeter-wave receivers employing sensitive SIS (Superconductor-Insulator- Superconductor) detector technology will provide new opportunities for precise passive remote sensing observation of minor constituents in atmosphere. Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) was designed to be onbord the Japanese Experiment Module (JEM) on the International Space Station (ISS) as a collaboration project of National Institute of Information and Communications Technology (NICT) and Japan Aerospace Exploration Agency (JAXA). SMILES scheduled to be launch in September 11, 2009 by the H-II Transfer Vehicle (HTV). Mission Objectives are: i) Space demonstration of superconductive mixer and 4-K mechanical cooler for the submillimeter limb emission sounding, and ii) global observations of atmospheric minor constituents. JEM/SMILES will allow to observe the atmospheric species such as O3, H35Cl, H37 Cl, ClO, BrO, HOCl, HO2, and HNO3, CH3CN, and Ozone isotope species with the precisions in a few to several tens percents from upper troposphere to the mesosphere. We have estimated the observation capabilities of JEM/SMILES. This new technology may allow us to open new issues in atmospheric science.

  8. Seismic Analysis Capability in NASTRAN

    NASA Technical Reports Server (NTRS)

    Butler, T. G.; Strang, R. F.

    1984-01-01

    Seismic analysis is a technique which pertains to loading described in terms of boundary accelerations. Earthquake shocks to buildings is the type of excitation which usually comes to mind when one hears the word seismic, but this technique also applied to a broad class of acceleration excitations which are applied at the base of a structure such as vibration shaker testing or shocks to machinery foundations. Four different solution paths are available in NASTRAN for seismic analysis. They are: Direct Seismic Frequency Response, Direct Seismic Transient Response, Modal Seismic Frequency Response, and Modal Seismic Transient Response. This capability, at present, is invoked not as separate rigid formats, but as pre-packaged ALTER packets to existing RIGID Formats 8, 9, 11, and 12. These ALTER packets are included with the delivery of the NASTRAN program and are stored on the computer as a library of callable utilities. The user calls one of these utilities and merges it into the Executive Control Section of the data deck to perform any of the four options are invoked by setting parameter values in the bulk data.

  9. Natural and Synthetic Polymers as Inhibitors of Drug Efflux Pumps

    PubMed Central

    2007-01-01

    Inhibition of efflux pumps is an emerging approach in cancer therapy and drug delivery. Since it has been discovered that polymeric pharmaceutical excipients such as Tweens® or Pluronics® can inhibit efflux pumps, various other polymers have been investigated regarding their potential efflux pump inhibitory activity. Among them are polysaccharides, polyethylene glycols and derivatives, amphiphilic block copolymers, dendrimers and thiolated polymers. In the current review article, natural and synthetic polymers that are capable of inhibiting efflux pumps as well as their application in cancer therapy and drug delivery are discussed. PMID:17896100

  10. 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.

  11. Triclosan antimicrobial polymers

    PubMed Central

    Petersen, Richard C.

    2016-01-01

    Triclosan antimicrobial molecular fluctuating energies of nonbonding electron pairs for the oxygen atom by ether bond rotations are reviewed with conformational computational chemistry analyses. Subsequent understanding of triclosan alternating ether bond rotations is able to help explain several material properties in Polymer Science. Unique bond rotation entanglements between triclosan and the polymer chains increase both the mechanical properties of polymer toughness and strength that are enhanced even better through secondary bonding relationships. Further, polymer blend compatibilization is considered due to similar molecular relationships and polarities. With compatibilization of triclosan in polymers a more uniform stability for nonpolar triclosan in the polymer solid state is retained by the antimicrobial for extremely low release with minimum solubility into aqueous solution. As a result, triclosan is projected for long extended lifetimes as an antimicrobial polymer additive. Further, triclosan rapid alternating ether bond rotations disrupt secondary bonding between chain monomers in the resin state to reduce viscosity and enhance polymer blending. Thus, triclosan is considered for a polymer additive with multiple properties to be an antimicrobial with additional benefits as a nonpolar toughening agent and a hydrophobic wetting agent. The triclosan material relationships with alternating ether bond rotations are described through a complete different form of medium by comparisons with known antimicrobial properties that upset bacterial cell membranes through rapid fluctuating mechanomolecular energies. Also, triclosan bond entanglements with secondary bonding can produce structural defects in weak bacterial lipid membranes requiring pliability that can then interfere with cell division. Regarding applications with polymers, triclosan can be incorporated by mixing into a resin system before cure, melt mixed with thermoplastic polymers that set on cooling

  12. Extension of TRIGA reactor capabilities

    SciTech Connect

    Gietzen, A.J.

    1980-07-01

    The first TRIGA reactor went into operation at 10 kW about 22 years ago. Since that time 55 TRIGAs have been put into operation including steady-state powers up to 14,000 kW and pulsing reactors that pulse to 20,000,000 kW. Five more are under construction and a proposal will soon be submitted for a reactor of 25,000 kW. Along with these increases in power levels (and the corresponding fluxes) the experimental facilities have also been expanded. In addition to the installation of new TRIGA reactors with enhanced capabilities many of the older reactors have been modified and upgraded. Also, a number of reactors originally fueled with plate fuel were converted to TRIGA fuel to take advantage of the improved technical and safety characteristics, including the ability for pulsed operation. In order to accommodate increased power and performance the fuel has undergone considerable evolution. Most of the changes have been in the geometry, enrichment and cladding material. However, more recently further development on the UZrH alloy has been carried out to extend the uranium content up to 45% by weight. This increased U content is necessary to allow the use of less than 20% enrichment in the higher powered reactors while maintaining longer core lifetime. The instrumentation and control system has undergone remarkable improvement as the electronics technology has evolved so rapidly in the last two decades. The information display and the circuitry logic has also undergone improvements for enhanced ease of operation and safety. (author)

  13. Capability engineering: transforming defence acquisition in Canada

    NASA Astrophysics Data System (ADS)

    Pagotto, Jack; Walker, Robert S.

    2004-07-01

    Capability engineering, a new methodology with the potential to transform defence planning and acquisition, is described. The impact of capability engineering on existing defence business processes and organizations is being explored in Canada during the course of a four-year Technology Demonstration Project called Collaborative Capability Definition, Engineering and Management (CapDEM). Having completed the first of three experimentation spirals within this project, a high-level capability engineering process model has been defined. The process begins by mapping strategic defence guidance onto defence capabilities, using architectural models that articulate the people, process and materiel requirements of each capability when viewed as a system-of-systems. For a selected capability, metrics are rigorously applied to these models to assess their ability to deliver the military capability outcomes required by a set of predefined tasks and force planning scenarios. By programming the modification of these tasks and planning scenarios over time according to evolving capability objectives, quantifiable capability gaps are identified, that in turn drive the process towards options to close these gaps. The implementation plan for these options constitutes a capability evolution roadmap to support defence-investment decisions. Capability engineering is viewed as an essential enabler to meeting the objective of improved capability management, subsuming the functions of capability generation, sustainment and employment.

  14. CD44-Targeted Hyaluronic Acid-Coated Redox-Responsive Hyperbranched Poly(amido amine)/Plasmid DNA Ternary Nanoassemblies for Efficient Gene Delivery.

    PubMed

    Gu, Jijin; Chen, Xinyi; Ren, Xiaoqing; Zhang, Xiulei; Fang, Xiaoling; Sha, Xianyi

    2016-07-20

    Hyaluronic acid (HA), which can specifically bind to CD44 receptor, is a specific ligand for targeting to CD44-overexpressing cancer cells. The current study aimed to develop ternary nanoassemblies based on HA-coating for targeted gene delivery to CD44-positive tumors. A novel reducible hyperbranched poly(amido amine) (RHB) was assembled with plasmid DNA (pDNA) to form RHB/pDNA nanoassemblies. HA/RHB/pDNA nanoassemblies were fabricated by coating HA on the surface of the RHB/pDNA nanoassembly core through electrostatic interaction. After optimization, HA/RHB/pDNA nanoassemblies were spherical, core-shell nanoparticles with nanosize (187.6 ± 11.4 nm) and negative charge (-9.1 ± 0.3 mV). The ternary nanoassemblies could efficiently protect the condensed pDNA from enzymatic degradation by DNase I, and HA could significantly improve the stability of nanoassemblies in the sodium heparin solution or serum in vitro. As expected, HA significantly decreased the cytotoxicity of RHB/pDNA nanoassemblies due to the negative surface charges. Moreover, it revealed that HA/RHB/pDNA nanoassemblies showed higher transfection activity than RHB/pDNA nanoassemblies in B16F10 cells, especially in the presence of serum in vitro. Because of the active recognition between HA and CD44 receptor, there was significantly different transfection efficiency between B16F10 (CD44+) and NIH3T3 (CD44-) cells after treatment with HA/RHB/pDNA nanoassemblies. In addition, the cellular targeting and transfection activity of HA/RHB/pDNA nanoassemblies were further evaluated in vivo. The results indicated that the interaction between HA and CD44 receptor dramatically improved the accumulation of HA/RHB/pDNA nanoassemblies in CD44-positive tumor, leading to higher gene expression than RHB/pDNA nanoassemblies. Therefore, HA/RHB/pDNA ternary nanoassemblies may be a potential gene vector for delivery of therapeutic genes to treat CD44-overexpressing tumors in vivo. PMID:27311558

  15. Polymers Are Everywhere.

    ERIC Educational Resources Information Center

    Seymour, Raymond B.

    1988-01-01

    Describes the history of the human understanding of polymers from alchemy to modern times. Discusses renaissance chemistry, polymers in the nineteenth century, synthetic elastomers, thermoplastic elastomers, fibers, coatings, adhesives, derivatives of natural rubber, thermosets, step-reaction, and chain polymerization. (CW)

  16. Melons are Branched Polymers

    NASA Astrophysics Data System (ADS)

    Gurau, Razvan; Ryan, James P.

    2014-11-01

    Melonic graphs constitute the family of graphs arising at leading order in the 1/N expansion of tensor models. They were shown to lead to a continuum phase, reminiscent of branched polymers. We show here that they are in fact precisely branched polymers, that is, they possess Hausdorff dimension 2 and spectral dimension 4/3.

  17. Heat resistant polyphosphazene polymers

    NASA Technical Reports Server (NTRS)

    Fewell, L. L.; Allcock, H. R.; Obrien, J. P.; Scopelianos, A. G.

    1981-01-01

    Polymers of carboranyl substituted polyphosphazene are stable at high temperatures and produce insulating char upon pyrolysis. Substituted compounds are prepared by heat polymerizing carboranyl halophosphazene, which is obtained by reacting lithium carborane with, for example, hexachlorocyclotriphosphazene under anhydrous conditions. Chlorine of polymer may be replaced by aryloxy and alkoxy groups.

  18. Polymer based tunneling sensor

    NASA Technical Reports Server (NTRS)

    Cui, Tianhong (Inventor); Wang, Jing (Inventor); Zhao, Yongjun (Inventor)

    2006-01-01

    A process for fabricating a polymer based circuit by the following steps. A mold of a design is formed through a lithography process. The design is transferred to a polymer substrate through a hot embossing process. A metal layer is then deposited over at least part of said design and at least one electrical lead is connected to said metal layer.

  19. Porous polymer media

    DOEpatents

    Shepodd, Timothy J.

    2002-01-01

    Highly crosslinked monolithic porous polymer materials for chromatographic applications. By using solvent compositions that provide not only for polymerization of acrylate monomers in such a fashion that a porous polymer network is formed prior to phase separation but also for exchanging the polymerization solvent for a running buffer using electroosmotic flow, the need for high pressure purging is eliminated. The polymer materials have been shown to be an effective capillary electrochromatographic separations medium at lower field strengths than conventional polymer media. Further, because of their highly crosslinked nature these polymer materials are structurally stable in a wide range of organic and aqueous solvents and over a pH range of 2-12.

  20. Polymer Crystallization under Confinement

    NASA Astrophysics Data System (ADS)

    Floudas, George

    Recent efforts indicated that polymer crystallization under confinement can be substantially different from the bulk. This can have important technological applications for the design of polymeric nanofibers with tunable mechanical strength, processability and optical clarity. However, the question of how, why and when polymers crystallize under confinement is not fully answered. Important studies of polymer crystallization confined to droplets and within the spherical nanodomains of block copolymers emphasized the interplay between heterogeneous and homogeneous nucleation. Herein we report on recent studies1-5 of polymer crystallization under hard confinement provided by model self-ordered AAO nanopores. Important open questions here are on the type of nucleation (homogeneous vs. heterogeneous), the size of critical nucleus, the crystal orientation and the possibility to control the overall crystallinity. Providing answers to these questions is of technological relevance for the understanding of nanocomposites containing semicrystalline polymers. In collaboration with Y. Suzuki, H. Duran, M. Steinhart, H.-J. Butt.

  1. Rapid Polymer Sequencer

    NASA Technical Reports Server (NTRS)

    Stolc, Viktor (Inventor); Brock, Mathew W. (Inventor)

    2011-01-01

    Method and system for rapid and accurate determination of each of a sequence of unknown polymer components, such as nucleic acid components. A self-assembling monolayer of a selected substance is optionally provided on an interior surface of a pipette tip, and the interior surface is immersed in a selected liquid. A selected electrical field is impressed in a longitudinal or transverse direction at the tip, a polymer sequence is passed through the tip, and a change in an electrical current signal is measured as each polymer component passes through the tip. Each measured change in electrical current signals is compared with a database of reference signals, with each reference signal identified with a polymer component, to identify the unknown polymer component. The tip preferably has a pore inner diameter of no more than about 40 nm and is prepared by heating and pulling a very small section of a glass tubing.

  2. Polymers at membranes

    NASA Astrophysics Data System (ADS)

    Breidenich, Markus

    2000-11-01

    The surface of biological cells consists of a lipid membrane and a large amount of various proteins and polymers, which are embedded in the membrane or attached to it. We investigate how membranes are influenced by polymers, which are anchored to the membrane by one end. The entropic pressure exerted by the polymer induces a curvature, which bends the membrane away from the polymer. The resulting membrane shape profile is a cone in the vicinity of the anchor segment and a catenoid far away from it. The perturbative calculations are confirmed by Monte-Carlo simulations. An additional attractive interaction between polymer and membrane reduces the entropically induced curvature. In the limit of strong adsorption, the polymer is localized directly on the membrane surface and does not induce any pressure, i.e. the membrane curvature vanishes. If the polymer is not anchored directly on the membrane surface, but in a non-vanishing anchoring distance, the membrane bends towards the polymer for strong adsorption. In the last part of the thesis, we study membranes under the influence of non-anchored polymers in solution. In the limit of pure steric interactions between the membrane and free polymers, the membrane curves towards the polymers (in contrast to the case of anchored polymers). In the limit of strong adsorption the membrane bends away from the polymers. Die Oberfläche biologischer Zellen besteht aus einer Lipidmembran und einer Vielzahl von Proteinen und Polymeren, die in die Membran eingebaut sind. Die Beeinflussung der Membran durch Polymere, die mit einem Ende an der Membran verankert sind, wird im Rahmen dieser Arbeit anhand eines vereinfachten biomimetischen Systems studiert. Der entropische Druck, den das Polymer durch Stöße auf die Membran ausübt, führt dazu, dass sich die Membran vom Polymer weg krümmt. Die resultierende Membranform ist ein Kegel in der Nähe des Ankers und ein Katenoid in grossem Abstand vom Ankerpunkt. Monte Carlo-Simulationen best

  3. Megahertz organic/polymer diodes

    DOEpatents

    Katz, Howard Edan; Sun, Jia; Pal, Nath Bhola

    2012-12-11

    Featured is an organic/polymer diode having a first layer composed essentially of one of an organic semiconductor material or a polymeric semiconductor material and a second layer formed on the first layer and being electrically coupled to the first layer such that current flows through the layers in one direction when a voltage is applied in one direction. The second layer is essentially composed of a material whose characteristics and properties are such that when formed on the first layer, the diode is capable of high frequency rectifications on the order of megahertz rectifications such as for example rectifications at one of above 100KHz, 500KhZ, IMHz, or 10 MHz. In further embodiments, the layers are arranged so as to be exposed to atmosphere.

  4. Water-soluble polymers for recovery of metal ions from aqueous streams

    DOEpatents

    Smith, Barbara F.; Robison, Thomas W.

    1998-01-01

    A process of selectively separating a target metal contained in an aqueous solution by contacting the aqueous solution containing a target metal with an aqueous solution including a water-soluble polymer capable of binding with the target metal for sufficient time whereby a water-soluble polymer-target metal complex is formed, and, separating the solution including the water-soluble polymer-target metal complex from the solution is disclosed.

  5. Temperature-memory polymer actuators

    PubMed Central

    Behl, Marc; Kratz, Karl; Noechel, Ulrich; Sauter, Tilman; Lendlein, Andreas

    2013-01-01

    Reading out the temperature-memory of polymers, which is their ability to remember the temperature where they were deformed recently, is thus far unavoidably linked to erasing this memory effect. Here temperature-memory polymer actuators (TMPAs) based on cross-linked copolymer networks exhibiting a broad melting temperature range (ΔTm) are presented, which are capable of a long-term temperature-memory enabling more than 250 cyclic thermally controlled actuations with almost constant performance. The characteristic actuation temperatures Tacts of TMPAs can be adjusted by a purely physical process, guiding a directed crystallization in a temperature range of up to 40 °C by variation of the parameter Tsep in a nearly linear correlation. The temperature Tsep divides ΔTm into an upper Tm range (T > Tsep) forming a reshapeable actuation geometry that determines the skeleton and a lower Tm range (T < Tsep) that enables the temperature-controlled bidirectional actuation by crystallization-induced elongation and melting-induced contraction. The macroscopic bidirectional shape changes in TMPAs could be correlated with changes in the nanostructure of the crystallizable domains as a result of in situ X-ray investigations. Potential applications of TMPAs include heat engines with adjustable rotation rate and active building facades with self-regulating sun protectors. PMID:23836673

  6. Tension in Highly Branched Polymers

    NASA Astrophysics Data System (ADS)

    Rubinstein, Michael

    2012-02-01

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

  7. Local wettability modification by thermochemical nanolithography with write-read-overwrite capability

    NASA Astrophysics Data System (ADS)

    Wang, D. B.; Szoszkiewicz, R.; Lucas, M.; Riedo, E.; Okada, T.; Jones, S. C.; Marder, S. R.; Lee, J.; King, W. P.

    2007-12-01

    The wettability of a thin polymer film was modified twice by thermochemical nanolithography. By means of a first local chemical modification induced by an atomic force microscope tip heated to 110±20°C, hydrophilic patterns are written over an originally hydrophobic polymer surface. By further heating to 190±20°C, a second chemical modification reverses the local wettability change introduced by the first chemical modification. This write-read-overwrite capability can be particularly useful in the design of complex nanofluidic devices.

  8. Energy absorption capability and crashworthiness of composite material structures: A review

    SciTech Connect

    Carruthers, J.J.; Kettle, A.P.; Robinson, A.M.

    1998-10-01

    The controlled brittle failure of thermosetting fiber-reinforced polymer composites can provide a very efficient energy absorption mechanism. Consequently, the use of these materials in crashworthy vehicle designs has been the subject of considerable interest. In this respect, their more widespread application has been limited by the complexity of their collapse behavior. This article reviews the current level of understanding i this field, including the correlations between failure mode and energy absorption, the principal material, geometric, and physical parameters relevant to crashworthy design and methods of predicting the energy absorption capability of polymer composites. Areas which require further investigation are identified. This review article contains 70 references.

  9. Deformable membranes actuated by high mechanical power density composite electroactive polymers using tailored electric field

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y.; Bhattacharya, K.

    2003-01-01

    The objective of the project was to develop a versatile electroactuator based on a specific class of EAP, conductive polymer, that is capable of developing high forces and displacements in both bending and linear contraction/expansion movements.

  10. 47 CFR 95.655 - Frequency capability.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Frequency capability. 95.655 Section 95.655... SERVICES Technical Regulations Certification Requirements § 95.655 Frequency capability. (a) No transmitter will be certificated for use in the CB service if it is equipped with a frequency capability not...

  11. 47 CFR 95.655 - Frequency capability.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Frequency capability. 95.655 Section 95.655... SERVICES Technical Regulations Certification Requirements § 95.655 Frequency capability. (a) No transmitter will be certificated for use in the CB service if it is equipped with a frequency capability not...

  12. 47 CFR 95.655 - Frequency capability.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Frequency capability. 95.655 Section 95.655... SERVICES Technical Regulations Certification Requirements § 95.655 Frequency capability. (a) No transmitter will be certificated for use in the CB service if it is equipped with a frequency capability not...

  13. 47 CFR 95.655 - Frequency capability.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequency capability. 95.655 Section 95.655... SERVICES Technical Regulations Certification Requirements § 95.655 Frequency capability. (a) No transmitter will be certificated for use in the CB service if it is equipped with a frequency capability not...

  14. 47 CFR 95.655 - Frequency capability.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequency capability. 95.655 Section 95.655... SERVICES Technical Regulations Certification Requirements § 95.655 Frequency capability. (a) No transmitter will be certificated for use in the CB service if it is equipped with a frequency capability not...

  15. Selecting Capabilities for Quality of Life Measurement

    ERIC Educational Resources Information Center

    Robeyns, Ingrid

    2005-01-01

    The capability approach advocates that interpersonal comparisons be made in the space of functionings and capabilities. However, Amartya Sen has not specified which capabilities should be selected as the relevant ones. This has provoked two types of criticism. The stronger critique is Martha Nussbaum's claim that Sen should endorse one specific…

  16. Bottlebrush Polymer Additives for Binary Polymer Blends

    NASA Astrophysics Data System (ADS)

    Mah, Hui Zhen; Afzali, Pantea; Phan, Hanh; Qi, Luqing; Pesek, Stacy; Verduzco, Rafael; Stein, Gila

    Bottlebrush polymers are highly branched polymers that have been used in applications such as self-assembling photonics, drug delivery and stimuli-responsive surface coatings. However, they have not been widely studied as compatibilizers for polymer blends. In this study, bottlebrush polymers with poly(styrene-r-methyl methacrylate) side chains were used as additives for thin film blends of polystyrene (PS) and poly (methyl methacrylate) (PMMA). The blends were heated above the glass transition temperature to drive phase separation, and the resulting morphology was characterized with atomic force microscopy and optical microscopy. Outcomes were compared with PS/PMMA blends that contain conventional compatibilizers such as linear random copolymers of poly(styrene-r-methyl methacrylate) and diblock PS-PMMA copolymers. The bottlebrush additive accumulates at the PS/PMMA interface and drives the formation of vesicle-like droplets that assemble into longer chains. The continuity of the chains depends on the blend composition, where a network structure is achieved close to the critical composition. This unusual microstructure was not observed with the other additives, and may be a consequence of preferential wetting of the bottlebrush by the PS phase.

  17. New capabilities and applications for electrophoretically deposited coatings

    SciTech Connect

    Sharp, D.J.

    1991-01-01

    Our primary purpose in this test is to provide a brief general description of a few applications of various electrophoretic systems which have been investigated and have found use in various coating applications at Sandia National Laboratories. Both organic and inorganic suspensions in aqueous and non-aqueous media have been considered in these studies. Applications include high voltage insulating dielectrics, thermally conductive/electrically insulating films, adherent lubricating films, uniform photoresist films, glass coatings, and fissile uranium oxide/carbon composite films for studies of nuclear powered lasers. More recently, we have become interested in the beneficial environmental aspects of being able to provide protective polymer coatings which reduce or minimize the use of organic solvents required by traditional spray coat processes. Important practical factors which relate to film uniformity, adhesion, and composition are related to unique coating or plating capabilities and applications. 6 refs., 2 figs., 1 tab.

  18. Teaching polymers to fold

    SciTech Connect

    Judson, R.S. )

    1992-12-10

    A new method is presented for predicting folding pathways of polymers. The folding pathway is described as a generic program or sequence of logical steps of such a form that a computer can carry them out to produce a folded structure. A genetic (GA) is used to learn specific sequences or folding pathways that carry a denatured conformation into a target final conformation. The method is demonstrated on a model 2-dimensional polymer for which the global energy minimum is known. The GA learns a program that will fold a denatured polymer into its global energy minimum conformation. 27 refs., 4 figs.

  19. Low Dielectric Polymers

    NASA Technical Reports Server (NTRS)

    Venumbaka, Sreenivasulu R.; Cassidy, Patrick E.

    2002-01-01

    This report summarizes results obtained from research funded through Research Cooperative Agreement No. NCC-1-01033-"Low Dielectric Polymers" (from 5/10/01 through 5/09/02). Results are reported in three of the proposed research areas (Tasks 1-3 in the original proposal): (1) Repeat and confirm the preparation and properties of the new alkyl-substituted PEK, 6HC17-PEK, (2) Prepare and evaluate polymers derived from a highly fluorinated monomer, and (3) Prepare and evaluate new silicon and/or fluorine-containing polymers expected to retain useful properties at low temperature.

  20. Soluble porphyrin polymers

    DOEpatents

    Gust, Jr., John Devens; Liddell, Paul Anthony

    2015-07-07

    Porphyrin polymers of Structure 1, where n is an integer (e.g., 1, 2, 3, 4, 5, or greater) ##STR00001## are synthesized by the method shown in FIGS. 2A and 2B. The porphyrin polymers of Structure 1 are soluble in organic solvents such as 2-MeTHF and the like, and can be synthesized in bulk (i.e., in processes other than electropolymerization). These porphyrin polymers have long excited state lifetimes, making the material suitable as an organic semiconductor for organic electronic devices including transistors and memories, as well as solar cells, sensors, light-emitting devices, and other opto-electronic devices.