Advanced Materials

Cover image for Advanced Materials

July 17, 2008

Volume 20, Issue 14

Pages 2655–2796

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Communications
    6. Index
    1. Cover Picture: Supramolecular Organization and Photovoltaics of Triangle-shaped Discotic Graphenes with Swallow-tailed Alkyl Substituents (Adv. Mater. 14/2008)

      Xinliang Feng, Miaoyin Liu, Wojciech Pisula, Masayoshi Takase, Jiaoli Li and Klaus Müllen

      Article first published online: 23 JUL 2008 | DOI: 10.1002/adma.200890054

      Thumbnail image of graphical abstract

      The cover shows novel triangle-shaped discotic graphenes that are substituted by swallow-like alkyl tails and allow facile purification, control over thermotropic properties, and solution fabrication into efficient photovoltaic devices. Xinliang Feng, Wojciech Pisula, Klaus Mullen, and co-workers report on p. 2684 that this unique molecular design results in an extremely broad liquid-crystalline range and the ability to self-heal at low processing temperatures, which improves the performance of photovoltaic cells.

  2. Inside Front Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Communications
    6. Index
    1. Inside Front Cover: Manipulating the Local Light Emission in Organic Light-Emitting Diodes by using Patterned Self-Assembled Monolayers (Adv. Mater. 14/2008)

      Simon G. J. Mathijssen, Paul A. van Hal, Ton J. M. van den Biggelaar, Edsger C. P. Smits, Bert de Boer, Martijn Kemerink, René A. J. Janssen and Dago M. de Leeuw

      Article first published online: 23 JUL 2008 | DOI: 10.1002/adma.200890055

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      The inside cover shows an optical micrograph picture of an organic light-emitting diode with patterned, micro-contact-printed self-assembled monolayers (SAMs) that modify the work function of the anode, reported by Simon Mathijssen, Dago de Leeuw, and co-workers on p. 2703. In this particular light-emitting diode a fluorinated alkanethiol has been used that increases the work function and therefore improves the injection of holes. This results in a higher light emission on the positions where the SAM has been printed, which can be observed as the red pattern.

  3. Contents

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Communications
    6. Index
    1. Contents: (Adv. Mater. 14/2008) (pages 2655–2662)

      Article first published online: 23 JUL 2008 | DOI: 10.1002/adma.200890056

  4. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Communications
    6. Index
    1. Rapid and Reversible Hydrogen Storage in Clathrate Hydrates Using Emulsion-Templated Polymers (pages 2663–2666)

      Fabing Su, Christopher L. Bray, Bien Tan and Andrew I. Cooper

      Article first published online: 2 JUN 2008 | DOI: 10.1002/adma.200800550

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      A method for greatly accelerating the storage of gases such as hydrogen in clathrates by supporting the clathrate phase on a highly macroporous emulsion-templated polymer is presented. The gravimetric penalty is low due to the low bulk density of the support, no mechanical mixing is required, and the system is fully recyclable over multiple charge/ discharge cycles.

    2. The Patterning of Sub-500 nm Inorganic Oxide Structures (pages 2667–2673)

      Meredith J. Hampton, Stuart S. Williams, Zhilian Zhou, Janine Nunes, Doo-Hyun Ko, Joseph L. Templeton, Edward T. Samulski and Joseph M. DeSimone

      Article first published online: 2 JUN 2008 | DOI: 10.1002/adma.200702495

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      Elastomeric perfluoropolyether molds are applied to pattern arrays of sub-500 nm inorganic oxide features. This versatile soft-lithography technique can be used to pattern a wide range of materials; in this work inorganic oxides including TiO2, SnO2, ZnO, ITO, and BaTiO3 are patterned on a variety of substrates with different aspect ratios. An example of TiO2 posts is shown in the figure.

    3. Polyelectrolyte Films Boost Progenitor Cell Differentiation into Endothelium-like Monolayers (pages 2674–2678)

      Nicolas Berthelemy, Halima Kerdjoudj, Caroline Gaucher, Pierre Schaaf, Jean-François Stoltz, Patrick Lacolley, Jean-Claude Voegel and Patrick Menu

      Article first published online: 2 JUN 2008 | DOI: 10.1002/adma.200702418

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      Rapid differentiation of endothelial progenitor cells (EPCs) into confluent mature endothelial cells (see figure) is important in tissue engineering for the design of autologous, nonthrombotic, vascular grafts. A new method based on EPC culture on poly(sodium-4- styrene-sulfonate)/poly(allylamine hydrochloride), that is, polyelectrolyte-multilayer-coated substrates, reduces the time from two months to two weeks.

    4. Surfactant-Directed Synthesis of Branched Bismuth Telluride/Sulfide Core/Shell Nanorods (pages 2679–2683)

      Arup Purkayastha, Qingyu Yan, Makala S. Raghuveer, Darshan D. Gandhi, Huafang Li, Zhong W. Liu, Raju V. Ramanujan, Theodorian Borca-Tasciuc and Ganapathiraman Ramanath

      Article first published online: 2 JUN 2008 | DOI: 10.1002/adma.200702572

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      Branched core/shell bismuth telluride/bismuth sulfide nanorod heterostructures are prepared by using a biomimetic surfactant, L-glutathionic acid. Trigonal nanocrystals of bismuth telluride are encapsulated by nanoscopic shells of orthorhombic bismuth sulfide. Crystallographic twinning causes shell branching. Such heteronanostructures are attractive for thermoelectric power generation and cooling applications.

    5. Supramolecular Organization and Photovoltaics of Triangle-shaped Discotic Graphenes with Swallow-tailed Alkyl Substituents (pages 2684–2689)

      Xinliang Feng, Miaoyin Liu, Wojciech Pisula, Masayoshi Takase, Jiaoli Li and Klaus Müllen

      Article first published online: 2 JUN 2008 | DOI: 10.1002/adma.200800642

      Thumbnail image of graphical abstract

      Two novel triangle-shaped discotic graphenes with swallow-like alkyl tails are synthesized; these discotic graphenes allow facile purification, control over thermotropic properties, and solution fabrication into efficient photovoltaic devices. The unique molecular design results in an extremely broad liquid-crystalline range and the ability to self-heal at low processing temperatures, which improves the performance of photovoltaic cells.

    6. Core/Single-Crystal-Shell Nanospheres for Controlled Drug Release via a Magnetically Triggered Rupturing Mechanism (pages 2690–2695)

      Shang-Hsiu Hu, San-Yuan Chen, Dean-Mo Liu and Chi-Sheng Hsiao

      Article first published online: 2 JUN 2008 | DOI: 10.1002/adma.200800193

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      Core/single-crystal-shell nanospheres are constructed from a poly-(N-vinyl- 2-pyrrolidone) (PVP)-modified silica core with an outer layer of single-crystal iron oxide shell. The nanospheres show outstanding release-and-zero-release characteristics via the addition and removal, respectively, of an external high-frequency magnetic field.

    7. White Light-Emitting Diodes with Excellent Color Rendering Based on Organically Capped CdSe Quantum Dots and Sr3SiO5:Ce3+,Li+ Phosphors (pages 2696–2702)

      Ho Seong Jang, Heesun Yang, Sung Wook Kim, Ji Yeon Han, Sang-Geun Lee and Duk Young Jeon

      Article first published online: 2 JUN 2008 | DOI: 10.1002/adma.200702846

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      White LEDs are fabricated through a combination of blue LEDs with Sr3SiO5:Ce3+,Li+ phosphors and organically capped CdSe quantum dots (QDs), which exhibit a 2D superlattice. The combination of blue emission from the LEDs, greenish-yellow emission from the phosphors, and red emission from the QDs generates white light. As-synthesized white LEDs show excellent color rendering properties and stable color coordinates against increasing forward bias currents (see figure).

    8. Manipulating the Local Light Emission in Organic Light-Emitting Diodes by using Patterned Self-Assembled Monolayers (pages 2703–2706)

      Simon G. J. Mathijssen, Paul A. van Hal, Ton J. M. van den Biggelaar, Edsger C. P. Smits, Bert de Boer, Martijn Kemerink, René A. J. Janssen and Dago M. de Leeuw

      Article first published online: 2 JUN 2008 | DOI: 10.1002/adma.200800299

      Thumbnail image of graphical abstract

      Patterned organic light-emitting diodes are fabricated by using microcontact- printed self-assembled monolayers on a gold anode (see background figure). Molecules with dipole moments in opposite directions result in an increase or a decrease of the local work function (foreground picture), providing a direct handle on charge injection and enabling local modification of the light emission.

    9. Fabrication and Characterization of Ultrahigh-Volume- Fraction Aligned Carbon Nanotube–Polymer Composites (pages 2707–2714)

      Brian L. Wardle, Diego S. Saito, Enrique J. García, A. John Hart, Roberto Guzmán de Villoria and Eric A. Verploegen

      Article first published online: 5 JUN 2008 | DOI: 10.1002/adma.200800295

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      Aligned CNT nanocomposites with variable volume fraction, up to 20%, are demonstrated. Biaxial mechanical densification of aligned CNT forests, followed by capillarity-driven wetting using unmodified aerospace-grade polymers, creates centimeter-scale specimens. Characterizations confirm CNT alignment and dispersion in the thermosets, providing a useful platform for controlled nanoscale interaction and nanocomposite property studies that emphasize anisotropy.

    10. From Ambi- to Unipolar Behavior in Discotic Dye Field-Effect Transistors (pages 2715–2719)

      Hoi Nok Tsao, Wojciech Pisula, Zhihong Liu, Wojciech Osikowicz, William R. Salaneck and Klaus Müllen

      Article first published online: 5 JUN 2008 | DOI: 10.1002/adma.200702992

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      Ambipolar, solution-processed thin-film transistors based on a discotic dye turn into unipolar behavior after thermal annealing. No evidence for temperature-induced change in injection barrier or interface trapping can be found to explain this phenomenon. Instead, a variation in morphology is considered as the cause for the observed transition from ambipolar to unipolar charge transport.

    11. Silicon-Cored Anthracene Derivatives as Host Materials for Highly Efficient Blue Organic Light-Emitting Devices (pages 2720–2729)

      Yi-Yeol Lyu, Jeonghun Kwak, Ohyun Kwon, Soo-Hyoung Lee, Doyun Kim, Changhee Lee and Kookheon Char

      Article first published online: 2 JUN 2008 | DOI: 10.1002/adma.200602885

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      Blue host materials for organic light-emitting diodes (OLEDs) based on silicon-cored (tetraphenylsilane) anthracene derivatives are synthesized (see figure). These compounds, with a non-coplanar molecular structure, have high glass-transition temperatures and good amorphous-film-forming capabilities. When doped with a blue-fluorescent dopant, blue emission with high color purity and high efficiency, up to 7.5 cd A−1 and 6.3%, is achieved.

    12. Gold-Nanoparticle-Enhanced Plasmonic Effects in a Responsive Polymer Gel (pages 2730–2734)

      Ihor Tokarev, Iryna Tokareva and Sergiy Minko

      Article first published online: 2 JUN 2008 | DOI: 10.1002/adma.200702885

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      Localized surface plasmon resonance excited in gold nanoparticles coupled with a responsive polymer gel is explored. A specially designed structure (vertically aligned cylindrical pores decorated with gold nanoparticles) of responsive polymer gel thin films allows for the transduction of external signal/ stimuli into a strong optical effect enhanced by interactions of gold nanoparticles.

    13. Organic Single-Crystalline Ribbons of a Rigid “H”-type Anthracene Derivative and High-Performance, Short-Channel Field-Effect Transistors of Individual Micro/Nanometer-Sized Ribbons Fabricated by an “Organic Ribbon Mask” Technique (pages 2735–2740)

      Lang Jiang, Jianhua Gao, Erjing Wang, Hongxiang Li, Zhaohui Wang, Wenping Hu and Lei Jiang

      Article first published online: 16 JUN 2008 | DOI: 10.1002/adma.200800341

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      The synthesis of a rigid, planar H-type anthracene derivative is described. Single-crystalline ribbons at micro- and nanometer sizes can be controllably produced and transistors based on an individual ribbon can be fabricated in situ through a newly developed “organic ribbon mask” method, in which the channel length of the transistors can be easily scaled down to sub-micrometer level.

    14. Tailoring Microporosity in Covalent Organic Frameworks (pages 2741–2746)

      R. William Tilford, Sam J. Mugavero III, Perry J. Pellechia and John J. Lavigne

      Article first published online: 5 JUN 2008 | DOI: 10.1002/adma.200800030

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      The microporosity of covalent organic frameworks (COFs) is tailored using a facile synthetic approach that introduces alkyl functionalities into the pore and generates networks with pore diameters between 1–2 nm. The added substituents significantly alter the host-guest properties of the resulting materials.

    15. Alq3 Nanorods: Promising Building Blocks for Optical Devices (pages 2747–2750)

      Wei Chen, Qing Peng and Yadong Li

      Article first published online: 5 JUN 2008 | DOI: 10.1002/adma.200702809

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      Monodisperse Alq3 nanorods with hexagonal-prism-like morphology are produced via a facile, emulsion based synthesis route. The photoluminescence of individual nanorods differs from the bulk material. These nanorods are promising building blocks for novel optical devices.

    16. Ultrathin Coatings with Change in Reactivity over Time Enable Functional In Vitro Networks Of Insect Neurons (pages 2751–2755)

      Anna Reska, Peter Gasteier, Petra Schulte, Martin Moeller, Andreas Offenhäusser and Juergen Groll

      Article first published online: 5 JUN 2008 | DOI: 10.1002/adma.200800270

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      It's just not cricket! A novel coating system that enables covalent attachment of biomolecules in a nonfouling environment without use of additional chemical crosslinkers is presented. Concanavalin A is patterned on the coatings to direct cell adhesion and growth of neurons from the cricket Gryllus bimaculatus and generate functional, patterned in vitro insect neuronal networks for the first time.

    17. Ammonia Borane Destabilized by Lithium Hydride: An Advanced On-Board Hydrogen Storage Material (pages 2756–2759)

      Xiangdong Kang, Zhanzhao Fang, Lingyan Kong, Huiming Cheng, Xiangdong Yao, Gaoqing Lu and Ping Wang

      Article first published online: 16 JUN 2008 | DOI: 10.1002/adma.200702958

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      An advanced hydrogen storage material, with potential for on-board application, is readily prepared by mechanically milling a 1:1 ammonia borane/lithium hydride (AB/LiH) mixture. The material possesses a H capacity of around 10 wt %, higher than the 2015 DOE gravimetric H capacity target, and can rapidly release over 7 wt % pure H2 at around 100 °C.

    18. Electric-Pulse-driven Electronic Phase Separation, Insulator–Metal Transition, and Possible Superconductivity in a Mott Insulator (pages 2760–2765)

      Cristian Vaju, Laurent Cario, Benoit Corraze, Etienne Janod, Vincent Dubost, Tristan Cren, Dimitri Roditchev, Daniel Braithwaite and Olivier Chauvet

      Article first published online: 5 JUN 2008 | DOI: 10.1002/adma.200702967

      Thumbnail image of graphical abstract

      Experimental evidence of a nonvolatile electric-pulse-induced insulator-to-metal transition and possible superconductivity in the Mott insulator GaTa4Se8 is reported. Scanning tunneling microscopy experiments show that this unconventional response of the system to short electric pulses arises from a nanometer-scale electronic phase separation generated in the bulk material (see figure).

    19. High-Performance Membranes from Polyimides with Intrinsic Microporosity (pages 2766–2771)

      Bader S. Ghanem, Neil B. McKeown, Peter M. Budd, James D. Selbie and Detlev Fritsch

      Article first published online: 16 JUN 2008 | DOI: 10.1002/adma.200702400

      Thumbnail image of graphical abstract

      Membranes with high permeability to gases are formed from polyimides with rigid backbones that incorporate a spiro-centre (see figure). A route to this new range of high-free-volume polyimides is demonstrated, and exceptional performance is obtained for a polymer containing a dimethyl binaphthyl unit.

    20. Spray Processable Green to Highly Transmissive Electrochromics via Chemically Polymerizable Donor–Acceptor Heterocyclic Pentamers (pages 2772–2776)

      Pierre M. Beaujuge, Stefan Ellinger and John R. Reynolds

      Article first published online: 12 JUN 2008 | DOI: 10.1002/adma.200800280

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      Electrochromic polymers (ECPs) of tunable green: Two symmetrical donor-acceptor based oligomers were designed, synthesized and chemically polymerized affording solution-processable conjugated polymers of distinct green hues in their neutral state. The polyheterocyclic hybrids exhibited highly transmissive oxidized states, excellent optical contrasts both in the visible and in the near infrared, fast switching times and long-term redox switching stability as expected for practical ECP devices.

    21. Titanate Nanofibers as Intelligent Absorbents for the Removal of Radioactive Ions from Water (pages 2777–2781)

      Dong Jiang Yang, Zhan Feng Zheng, Huai Yong Zhu, Hong Wei Liu and Xue Ping Gao

      Article first published online: 16 JUN 2008 | DOI: 10.1002/adma.200702055

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      Layered titanate nanofibers can absorb bivalent ions from waste water via an ion exchange process. The sorption induces a considerable deformation of the layered structure, thus trapping the cations in the fibers permanently. Therefore, the fibers are desirable sorbents for the removal of toxic, radioactive Ra2+ and Sr2+ ions from water and subsequent safe disposal thereof.

    22. Confinement-Induced Enhancement of Antigen–Antibody Interactions within Binary Nanopatterns to Achieve Higher Efficiency of On-Chip Immunosensors (pages 2782–2788)

      Sivashankar Krishnamoorthy and Michael Himmelhaus

      Article first published online: 16 JUN 2008 | DOI: 10.1002/adma.200702188

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      By combining molecular self-assembly, nanosphere lithography and reactive ion etching, large-scale nanopatterns of antibodies are fabricated for direct application in state-of-the-art on-chip immunosensors. Using in-situ surface plasmon resonance, the patterns are studied in view of their antigen binding capacity, which shows an increase of up to 120% solely in the case of antibody confinement into the nanopatches by means of a nonfouling embedding matrix (see figure).

    23. Self-Healing Anticorrosion Coatings Based on pH-Sensitive Polyelectrolyte/Inhibitor Sandwichlike Nanostructures (pages 2789–2794)

      Daria V. Andreeva, Dmitri Fix, Helmuth Möhwald and Dmitry G. Shchukin

      Article first published online: 16 JUN 2008 | DOI: 10.1002/adma.200800705

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      An anticorrosion layer of a smart polymer coating is developed. The nature and properties of the coating simultaneously provide three mechanisms of corrosion protection: passivation of the metal degradation by controlled release of an inhibitor, buffering of pH changes at the corrosive area by polyelectrolyte layers, and self-curing of the film defects due to the mobility of the polyelectrolyte constituents in the layer-by-layer assembly.

  5. Index

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Communications
    6. Index
    1. Author Index and Subject Index Adv. Mater. 14/2008 (pages 2795–2796)

      Article first published online: 23 JUL 2008 | DOI: 10.1002/adma.200890057

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