Advanced Materials

Cover image for Vol. 19 Issue 4

February, 2007

Volume 19, Issue 4

Pages 487–616

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Contents
    4. Review
    5. Communications
    6. Book Review
    7. Index
    1. Cover Picture: Bright White-Light Emission from Semiconductor Nanocrystals: by Chance and by Design (Adv. Mater. 4/2007)

      S. Sapra, S. Mayilo, T. A. Klar, A. L. Rogach and J. Feldmann

      Article first published online: 9 FEB 2007 | DOI: 10.1002/adma.200790014

      The synthesis and characterization of two bright white-light-emitting semiconductor nanocrystal (NC)-based systems is reported. CdS NCs emit white light because of the presence of surface states over the entire range of the visible spectrum, whereas CdSe/ZnS/CdSe/ZnS core/shell/shell/shell NCs are designed to emit white light as a result of the combination of blue and orange emissions from the shell and the core, respectively (see figure).

  2. Contents

    1. Top of page
    2. Cover Picture
    3. Contents
    4. Review
    5. Communications
    6. Book Review
    7. Index
    1. Contents: Adv. Mater. 4/2007 (pages 487–494)

      Article first published online: 9 FEB 2007 | DOI: 10.1002/adma.200790012

  3. Review

    1. Top of page
    2. Cover Picture
    3. Contents
    4. Review
    5. Communications
    6. Book Review
    7. Index
    1. Nanoimprint Lithography: Methods and Material Requirements (pages 495–513)

      L. J. Guo

      Article first published online: 25 JAN 2007 | DOI: 10.1002/adma.200600882

      Thumbnail image of graphical abstract

      Nanoimprint lithography (see figure) is an emerging lithographic technique for high-throughput patterning of polymer nanostructures at high resolutions and low costs. This Review article considers the basic principles of nanoimprinting, with an emphasis on the requirements placed on materials to allow successful and reliable nanostructure replication.

  4. Communications

    1. Top of page
    2. Cover Picture
    3. Contents
    4. Review
    5. Communications
    6. Book Review
    7. Index
    1. Spatiotemporally Controlled Formation of Two-Component Counterpropagating Lateral Graft Density Gradients of Mixed Polymer Brushes on Planar Au Surfaces (pages 515–520)

      X. J. Wang and P. W. Bohn

      Article first published online: 24 JAN 2007 | DOI: 10.1002/adma.200601516

      Thumbnail image of graphical abstract

      A facile method to template mixed polymer-brush gradients onto a Au surface using a “grafting-from” atom-transfer radical polymerization coupled with an in-plane electrochemical-potential gradient is developed and studied (see figure), PNIPAAm: poly(N-isopropylacrylamide); PHEMA: poly(2-hydroxyethyl methacrylate). Polymer-brush gradients can be easily formed with tunable slope and transition-region width in a wide range of physical sizes by combining these methods.

    2. Polydiacetylene Supramolecules in Electrospun Microfibers: Fabrication, Micropatterning, and Sensor Applications (pages 521–524)

      S. K. Chae, H. Park, J. Yoon, C. H. Lee, D. J. Ahn and J.-M. Kim

      Article first published online: 25 JAN 2007 | DOI: 10.1002/adma.200602012

      Thumbnail image of graphical abstract

      Polymer microfibers encapsulating polydiacetylene (PDA) supramolecules (see figure) are prepared by using the electrospinning technique. Randomly distributed diacetylene monomers are found to self-assemble during fiber formation and enable the generation of blue-colored PDA-containing polymer fibers upon UV irradiation. Micropatterned images with a single fiber as well as the feasibility of a fiber-based sensor are demonstrated.

    3. High-Performance, Vertical-Type Organic Transistors with Built-In Nanotriode Arrays (pages 525–530)

      K. Fujimoto, T. Hiroi, K. Kudo and M. Nakamura

      Article first published online: 25 JAN 2007 | DOI: 10.1002/adma.200601736

      Thumbnail image of graphical abstract

      Organic static induction transistors with built-in nanotriode arrays formed in the lateral direction can be fabricated by using a colloidal-lithography technique, avoiding the need to use photolithography. The devices (see figure) demonstrate low operating voltages, high current output, and large transconductance, even though they use low-carrier-mobility materials.

    4. Molecular Design on Highly Efficient White Electroluminescence from a Single-Polymer System with Simultaneous Blue, Green, and Red Emission (pages 531–535)

      J. Liu, Z. Y. Xie, Y. X. Cheng, Y. H. Geng, L. X. Wang, X. B. Jing and F. S. Wang

      Article first published online: 24 JAN 2007 | DOI: 10.1002/adma.200601580

      Thumbnail image of graphical abstract

      A highly efficient white electroluminescent polymer with simultaneous blue, green, and red emission is reported, developed using a dopant/host strategy by covalently attaching both a green- and a red-light-emitting dopant to the side chain of a blue-light-emitting polymer host (see figure). In a single-layer device a maximum luminance efficiency of 7.3 cd A–1 with CIE coordinates of (0.31,0.32) is achieved.

    5. Single-Molecule Nanomaterials from π-Stacked Side-Chain Conjugated Polymers (pages 536–542)

      S. A. Jenekhe, M. M. Alam, Y. Zhu, S. Jiang and A. V. Shevade

      Article first published online: 25 JAN 2007 | DOI: 10.1002/adma.200601530

      Thumbnail image of graphical abstract

      Single-molecule semiconductor nanomaterials with π-stacked structures in solution and the solid state are prepared from a polystyrene backbone and densely tethered π-conjugated polyquinoline side chains (see figure). Highly structured optical absorption spectra and exclusive broad, structureless yellow excimer emission in toluene solutions confirm the π-stacked structures and collective optical properties of the side-chain conjugated polymers.

    6. Observation of van der Waals Driven Self-Assembly of MoSI Nanowires into a Low-Symmetry Structure Using Aberration-Corrected Electron Microscopy (pages 543–547)

      V. Nicolosi, P. D. Nellist, S. Sanvito, E. C. Cosgriff, S. Krishnamurthy, W. J. Blau, M. L. H. Green, D. Vengust, D. Dvorsek, D. Mihailovic, G. Compagnini, J. Sloan, V. Stolojan, J. D. Carey, S. J. Pennycook and J. N. Coleman

      Article first published online: 24 JAN 2007 | DOI: 10.1002/adma.200601867

      Thumbnail image of graphical abstract

      The packing structure of bundled MoSI nanowires is investigated. Scanning and high-resolution transmission electron microscopy are used to determine both the nanowire structure and bundle superstructure. Shown is a high-resolution microscopy image of a small bundle. The image width is 8 nm. It is found that the nanowires pack in crystalline bundles defined by the P1equation image (#2) spacegroup.

    7. Sequential Growth of Magic-Size CdSe Nanocrystals (pages 548–552)

      S. Kudera, M. Zanella, C. Giannini, A. Rizzo, Y. Li, G. Gigli, R. Cingolani, G. Ciccarella, W. Spahl, W. J. Parak and L. Manna

      Article first published online: 24 JAN 2007 | DOI: 10.1002/adma.200601015

      Thumbnail image of graphical abstract

      CdSe nanocrystals of well-defined sizes (so-called magic-size clusters, MSCs) have been grown with progressively larger sizes. During the synthesis, the relative populations of the different families of MSCs vary, as smaller clusters evolve into larger clusters. The time evolution of the various MSCs (see figure) is modeled by taking into account their much higher stability over nanocrystals of any intermediate size. A blue-light-emitting diode based on these MSCs is also presented.

    8. Nanoscale Engineering of Biomaterial Surfaces (pages 553–557)

      A. M. Lipski, C. Jaquiery, H. Choi, D. Eberli, M. Stevens, I. Martin, I.-W. Chen and V. P. Shastri

      Article first published online: 25 JAN 2007 | DOI: 10.1002/adma.200502617

      Thumbnail image of graphical abstract

      Single-step independent modification of the texture and chemistry of a material surface through the assembly of functionalized silica nanoparticles (NPs) is described. Such NP surface modifications enhance the differentiation of human-marrow-derived mesenchymal cells into an osteogenic lineage and present a new paradigm for nanoscale biomimetic engineering of a biomaterial surface.

    9. A Nonclassical Approach to Oligoacenes: Crossconjugated Nonplanar Poly(acene) Precursors (pages 558–560)

      H. Wang, C. Schaffner-Hamann, F. Marchioni and F. Wudl

      Article first published online: 25 JAN 2007 | DOI: 10.1002/adma.200502131

      Thumbnail image of graphical abstract

      A series of crossconjugated ladder polymers and oligomers (see figure) are synthesized by a one-step palladium-catalyzed polycondensation reaction. The polymers are soluble in various organic solvents owing to their nonplanar structure. The structure and physical properties of these compounds are investigated, and indicate that the π-electrons are mainly localized within anthraquinodimethane units of the structures.

    10. Cookie-like Au/NiO Nanoparticles with Optical Gas-Sensing Properties (pages 561–564)

      G. Mattei, P. Mazzoldi, M. L. Post, D. Buso, M. Guglielmi and A. Martucci

      Article first published online: 25 JAN 2007 | DOI: 10.1002/adma.200600930

      Thumbnail image of graphical abstract

      Cookie-like Au/NiO nanoparticles are grown inside a porous SiO2 sol–gel film (see figure). High-resolution TEM measurements reveal a twofold structure of the nanoparticles, showing a sharp interface with epitaxial coherence of the two phases. The nanocomposite films show a reversible change in optical absorbance in the vis-NIR wavelength range when exposed to carbon monoxide.

    11. Reversible Tuning of Lasing in Cholesteric Liquid Crystals Controlled by Light-Emitting Diodes (pages 565–568)

      G. Chilaya, A. Chanishvili, G. Petriashvili, R. Barberi, R. Bartolino, G. Cipparrone, A. Mazzulla and P. V. Shibaev

      Article first published online: 25 JAN 2007 | DOI: 10.1002/adma.200600353

      Thumbnail image of graphical abstract

      The lasing wavelength of dye-doped cholesteric liquid-crystal lasers is optically tuned by the reversible photoisomerization of the azo- or azoxy- nematic components of the cholesteric mixture. The figure demonstrates that the laser can be tuned over a range of almost 70 nm. The nematic components are easily and reversibly isomerized by illumination from light-emitting diodes at 405 and 466 nm.

    12. Bright White-Light Emission from Semiconductor Nanocrystals: by Chance and by Design (pages 569–572)

      S. Sapra, S. Mayilo, T. A. Klar, A. L. Rogach and J. Feldmann

      Article first published online: 24 JAN 2007 | DOI: 10.1002/adma.200602267

      Thumbnail image of graphical abstract

      The synthesis and characterization of two bright white-light-emitting semiconductor nanocrystal (NC)-based systems is reported. CdS NCs emit white light because of the presence of surface states over the entire range of the visible spectrum, whereas CdSe/ZnS/CdSe/ZnS core/shell/shell/shell NCs are designed to emit white light as a result of the combination of blue and orange emissions from the shell and the core, respectively (see figure).

    13. Single-Molecule I2@US-Tube Nanocapsules: A New X-ray Contrast-Agent Design (pages 573–576)

      J. M. Ashcroft, K. B. Hartman, K. R. Kissell, Y. Mackeyev, S. Pheasant, S. Young, P. A. W. Van der Heide, A. G. Mikos and L. J. Wilson

      Article first published online: 25 JAN 2007 | DOI: 10.1002/adma.200601424

      Thumbnail image of graphical abstract

      Single-molecule-like carbon nanocapsules derived from I2-filled ultrashort single-walled carbon nanotubes (US-tubes) have been prepared and characterized as a new paradigm in X-ray contrast-agent design. Functionalized by Bingel chemistry with external malonodiserinolamide  (Ser) groups, the new I2@US-tube (Ser)n species are water-soluble (0.25 mg mL–1) and more than twice as X-ray opaque as their empty US-tube(Ser) precursors.

    14. Photonic Crystals from Monodisperse Lanthanide-Hydroxide-at-Silica Core/Shell Colloidal Spheres (pages 577–580)

      Y.-S. Lin, Y. Hung, H.-Y. Lin, Y.-H. Tseng, Y.-F. Chen and C.-Y. Mou

      Article first published online: 24 JAN 2007 | DOI: 10.1002/adma.200601371

      Thumbnail image of graphical abstract

      A facile one-pot synthesis of size- controlled monodisperse lanthanide- hydroxide-at-SiO2 core/shell colloids is reported. The base-synthesized lanthanide-hydroxide-at-SiO2 particles are nonsticky enough to be well-suspended in solution, and they self-organize into 3D photonic crystals (see figure) that show a strong suppression of spontaneous emission in the photonic stop band.

    15. Localized Pressure-Induced Ferroelectric Pattern Arrays of Semicrystalline Poly(vinylidene fluoride) by Microimprinting (pages 581–586)

      S. J. Kang, Y. J. Park, J. Y. Hwang, H. J. Jeong, J. S. Lee, K. J. Kim, H.-C. Kim, J. Huh and C. Park

      Article first published online: 24 JAN 2007 | DOI: 10.1002/adma.200601474

      Thumbnail image of graphical abstract

      A polymer ferroelectric array embedded in an insulating paraelectric medium, with potential uses in nonvolatile memories, is fabricated by microimprinting poly(vinylidene fluoride) (PVDF) a patterned poly(dimethylsiloxane) with mold. The localized pressure induces a polymorphic transition into ferroelectric γ-type PVDF, whereas the unpressed raised areas (see figure) remain of the α type (paraelectric).

    16. Induced Orientational Order in Symmetric Diblock Copolymer Thin Films (pages 587–591)

      R. Ruiz, R. L. Sandstrom and C. T. Black

      Article first published online: 25 JAN 2007 | DOI: 10.1002/adma.200600287

      Thumbnail image of graphical abstract

      A new polymer multilayer fabrication method that employs employing thin films of lamellar polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) is presented. The effectiveness of the technique is demonstrated by patterning nanometer-scale silicon wire arrays. A multilayer patterning process that features defect-free lamellar pattern formation is demonstrated (see figure).

    17. An Extremely Low Methanol Crossover and Highly Durable Aromatic Pore-Filling Electrolyte Membrane for Direct Methanol Fuel Cells (pages 592–596)

      T. Yamaguchi, H. Zhou, S. Nakazawa and N. Hara

      Article first published online: 9 FEB 2007 | DOI: 10.1002/adma.200601086

      Thumbnail image of graphical abstract

      A highly durable pore-filling-type electrolyte membrane for direct methanol fuel cells has been developed from a porous polyimide substrate and a wholly aromatic hydrocarbon (see figure). The membrane succeeds in reducing the methanol crossover to several hundred times lower than that of a commercial Nafion membrane.

    18. Fabrication of Hollow Carbon Nanospheres Encapsulating Platinum Nanoparticles Using a Photocatalytic Reaction (pages 597–601)

      Y. H. Ng, S. Ikeda, T. Harada, S. Higashida, T. Sakata, H. Mori and M. Matsumura

      Article first published online: 25 JAN 2007 | DOI: 10.1002/adma.200601978

      Thumbnail image of graphical abstract

      The fabrication of Pt nanoparticles encapsulated in hollow carbon nanospheres using TiO2 nanoparticles as both the photocatalyst and the inorganic mold is demonstrated (see figure). These spheres are found to have high surface area and ultrathin shells with well-developed microporosity, and thus can be used as catalysts. This new imprinting method can be used to synthesize any desired nanostructures using predesigned TiO2 photocatalysts.

    19. Detection of Nucleic Acids Using Enzyme-Catalyzed Template-Guided Deposition of Polyaniline (pages 602–606)

      Z. Q. Gao, S. Rafea and L. H. Lim

      Article first published online: 25 JAN 2007 | DOI: 10.1002/adma.200601090

      Thumbnail image of graphical abstract

      An electrochemical procedure for the detection of nucleic acids is realized by utilizing polyaniline as a signal generator for the transduction of nucleic acid hybridization events (see figure). The unique combination of enzymatic amplification and template-guided deposition can be used in conjunction with other detection techniques, and the sensitivity of the biosensor increases with increasing time.

    20. Directed Assembly of Lamellae- Forming Block Copolymers by Using Chemically and Topographically Patterned Substrates (pages 607–611)

      S.-M. Park, M. P. Stoykovich, R. Ruiz, Y. Zhang, C. T. Black and P. F. Nealey

      Article first published online: 26 JAN 2007 | DOI: 10.1002/adma.200601421

      Thumbnail image of graphical abstract

      Lamellae-forming polystyrene-block-poly(methyl methacrylate) films were directed to assemble with perpendicularly oriented domains and long-range order in confining grooves (see figure), with preferential and neutral wetting in sidewalls and bottoms, respectively. The assembled films were highly amenable for pattern transfer by reactive-ion etching.

  5. Book Review

    1. Top of page
    2. Cover Picture
    3. Contents
    4. Review
    5. Communications
    6. Book Review
    7. Index
  6. Index

    1. Top of page
    2. Cover Picture
    3. Contents
    4. Review
    5. Communications
    6. Book Review
    7. Index
    1. Author Index and Subject Index Adv. Mater. 4/2007 (pages 615–616)

      Article first published online: 9 FEB 2007 | DOI: 10.1002/adma.200790013

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