Advanced Materials

Cover image for Vol. 19 Issue 16

August, 2007

Volume 19, Issue 16

Pages 2035–2178

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Review
    6. Communications
    7. Index
    1. Cover Picture: Conducting and Superhydrophobic Rambutan-like Hollow Spheres of Polyaniline (Adv. Mater. 16/2007)

      Y. Zhu, D. Hu, M. X. Wan, L. Jiang and Y. Wei

      Article first published online: 14 AUG 2007 | DOI: 10.1002/adma.200790059

      Thumbnail image of graphical abstract

      Superhydrophobic polyaniline (PANI) hollow spheres (see figure and cover) with high conductivity were self-assembled by using perfluorooctane sulfuric acid (PFOSA) as both dopant and soft template. It is proposed that these spheres are formed by a co-operative effect of two self-assembly processes: spherical micelles composed of PFOSA serve as a “microreactor” and PFOS/aniline salt micelles act as the soft template of the PANI nanofibers.

  2. Inside Front Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Review
    6. Communications
    7. Index
    1. Inside Front Cover: A Combined Top-Down/Bottom-Up Approach for the Nanoscale Patterning of Spin-Crossover Coordination Polymers (Adv. Mater. 16/2007)

      G. Molnár, S. Cobo, J. A. Real, F. Carcenac, E. Daran, C. Vieu and A. Bousseksou

      Article first published online: 14 AUG 2007 | DOI: 10.1002/adma.200790060

      Thumbnail image of graphical abstract

      Micro- and nanometer-sized patterns of the spin-crossover compound Fe(pyrazine)[Pt(CN)4] have been fabricated using a combination of lift-off and multilayer sequential assembly methods. These patterns (see figure and inside cover) exhibit a bistability of their electronic states and, thus, represent a novel platform for a wide array of potential applications.

  3. Contents

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Review
    6. Communications
    7. Index
    1. Contents: Adv. Mater. 16/2007 (pages 2035–2043)

      Article first published online: 14 AUG 2007 | DOI: 10.1002/adma.200790057

  4. Review

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Review
    6. Communications
    7. Index
    1. From One- to Three-Dimensional Organic Semiconductors: In Search of the Organic Silicon? (pages 2045–2060)

      J. Roncali, P. Leriche and A. Cravino

      Article first published online: 14 AUG 2007 | DOI: 10.1002/adma.200700135

      Thumbnail image of graphical abstract

      The anisotropic electronic properties of organic semiconductors based on 1D π-conjugated systems implies a control of molecular orientation that can pose specific problems for the fabrication of (opto)electronic devices by solution processes. This Review discusses emerging alternative strategies involving the development of organic semiconductors derived from 3D conjugated architectures and capable of exhibiting isotropic electronic properties.

  5. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Review
    6. Communications
    7. Index
    1. Confinement of Charge Carriers and Excitons in Electrophosphorescent Devices: Mechanism of Light Emission and Degradation (pages 2061–2066)

      B. D. Chin and C. Lee

      Article first published online: 11 JUL 2007 | DOI: 10.1002/adma.200602509

      Thumbnail image of graphical abstract

      Charge-carrier and exciton confinement is essential for efficiency and stability enhancment of electrophosphorescent devices. Emission-layer lifetimes of a 4,4′-N,N′-dicarbazole-biphenyl host doped with either a red- or green- emitting dye (upper and lower figures) show a strong dependence and near independence, respectively, on the type of exciton blocking layer used (four are shown). This is explained using energy- level differences and corresponding charge-trapping behavior.

    2. Flexible Polymer Colloidal-Crystal Lasers with a Light-Emitting Planar Defect (pages 2067–2072)

      S. Furumi, H. Fudouzi, H. T. Miyazaki and Y. Sakka

      Article first published online: 11 JUL 2007 | DOI: 10.1002/adma.200602855

      Thumbnail image of graphical abstract

      Flexible polymer laser devices excited by low-threshold optical light are fabricated from colloidal crystals (CCs; see figure). The laser-cavity structure consists of a light-emitting layer sandwiched between two polymer CC films. Optical excitation with a green beam brings about emission with a red beam. This process allows the production of ultralightweight, low-cost, flexible, and easily processible all-plastic lasers.

    3. Liquid Crystalline Phases from Polymer-Functionalized TiO2 Nanorods (pages 2073–2078)

      S. Meuer, P. Oberle, P. Theato, W. Tremel and R. Zentel

      Article first published online: 17 JUL 2007 | DOI: 10.1002/adma.200602516

      Thumbnail image of graphical abstract

      A general approach for the functionalization of inorganic nanoparticles with polymers is presented. The polymers for functionalization are designed to possess an anchor block and a soluble block. By this approach, TiO2 nanorods can be solubilized up to high concentrations in organic media. Owing to their anisotropic shape, liquid crystalline phases are formed, opening the possiblity of orienting the nanorods macroscopically.

    4. A Polymorph Lost and Found: The High-Temperature Crystal Structure of Pentacene (pages 2079–2082)

      T. Siegrist, C. Besnard, S. Haas, M. Schiltz, P. Pattison, D. Chernyshov, B. Batlogg and C. Kloc

      Article first published online: 17 JUL 2007 | DOI: 10.1002/adma.200602072

      Thumbnail image of graphical abstract

      A well-defined structural phase transformation is observed in bulk single crystals of pentacene, whereas pentacene powders heated above the phase-transformation temperature do not always fully convert, and upon cooling, coexistence of the two polymorphs is observed down to room temperature. The first-order phase transformation is isostructural: the close-packed herringbone-type layers shift against each other, keeping the same symmetry.

    5. Nonaqueous Sol–Gel Synthesis of a Nanocrystalline InNbO4 Visible-Light Photocatalyst (pages 2083–2086)

      L. Z. Zhang, I. Djerdj, M. Cao, M. Antonietti and M. Niederberger

      Article first published online: 20 JUL 2007 | DOI: 10.1002/adma.200700027

      Thumbnail image of graphical abstract

      InNbO4nanoparticles characterized by high crystallinity and particle sizes in the range of 10–30 nm (see TEM image) are synthesized by a soft-chemistry route involving the solvothermal reaction of indium acetylacetonate and niobium chloride in benzyl alcohol at 200 °C. The as-synthesized nanopowders offer a high photocatalytic activity under illumination with visible light.

    6. Superior Electrode Performance of Nanostructured Mesoporous TiO2 (Anatase) through Efficient Hierarchical Mixed Conducting Networks (pages 2087–2091)

      Y.-G. Guo, Y.-S. Hu, W. Sigle and J. Maier

      Article first published online: 24 JUL 2007 | DOI: 10.1002/adma.200602828

      Thumbnail image of graphical abstract

      An optimized nanostructure design of electrode material for high power, high energy lithium batteries is realized. Highly Li-permeable materials are obtained by introducing hierarchical mixed conducting networks on both nanoscale and microscale levels (see figure). A mesoporous TiO2:RuO2 composite is selected as an example of this new design.

    7. Conducting and Superhydrophobic Rambutan-like Hollow Spheres of Polyaniline (pages 2092–2096)

      Y. Zhu, D. Hu, M. X. Wan, L. Jiang and Y. Wei

      Article first published online: 17 JUL 2007 | DOI: 10.1002/adma.200602135

      Thumbnail image of graphical abstract

      Superhydrophobic polyaniline (PANI) hollow spheres (see figure and cover) with high conductivity were self-assembled by using perfluorooctane sulfuric acid (PFOSA) as both dopant and soft template. It is proposed that these spheres are formed by a co-operative effect of two self-assembly processes: spherical micelles composed of PFOSA serve as a “microreactor” and PFOS/aniline salt micelles act as the soft template of the PANI nanofibers.

    8. Growth and Electronic Transport in 9,10-Diphenylanthracene Single Crystals—An Organic Semiconductor of High Electron and Hole Mobility (pages 2097–2101)

      A. K. Tripathi, M. Heinrich, T. Siegrist and J. Pflaum

      Article first published online: 25 JUL 2007 | DOI: 10.1002/adma.200602162

      Thumbnail image of graphical abstract

      Electron and hole transport is demonstrated on bulk crystals of the organic semiconductor 9,10-diphenylanthracene (DPA). The high mobilities at room temperature for electrons (ca. 13 cm2 Vs–1) and holes (ca. 3.7 cm2 Vs–1) make DPA a prominent candidate for device applications. The hole mobility follows a bandlike transport at high temperatures (200K–400K) and a saturation behavior in the low-temperature regime (see figure), the latter being discussed in the context of various transport models.

    9. Fabrication of Ti–Al Micro/ Nanometer-Sized Porous Alloys through the Kirkendall Effect (pages 2102–2106)

      Y. H. He, Y. Jiang, N. P. Xu, J. Zou, B. Y. Huang, C. T. Liu and P. K. Liaw

      Article first published online: 25 JUL 2007 | DOI: 10.1002/adma.200602398

      Thumbnail image of graphical abstract

      A new method based on the Kirkendall effect is developed to fabricate Ti–Al porous alloys with open pores and adjustable pore size. This novel porous material (microstructures shown in the figure) has excellent pore size stability and outstanding corrosion and oxidation resistance. These exceptional advantages of fabricated Ti–Al porous alloys make them an ideal filtration candidate for rugged environments.

    10. Octupolar Films with Significant Second-Harmonic Generation (pages 2107–2111)

      M.-Y. Jeong, H. M. Kim, S.-J. Jeon, S. Brasselet and B. R. Cho

      Article first published online: 17 JUL 2007 | DOI: 10.1002/adma.200700414

      Thumbnail image of graphical abstract

      Octupolar films containing 1,3,5-tricyano-2,4,6-tris(p-diethylaminostyryl)benzene in a polymethylmetacrylate matrix are prepared by using free-casting and spin-coating methods and their physical properties are characterized by using polarization microscopy, X-ray diffraction spectra, and second-harmonic generation (see figure). The films exhibit an optimum molecular packing that can find useful applications in electro-optic devices.

    11. Low-Temperature In Situ Large-Strain Plasticity of Silicon Nanowires (pages 2112–2118)

      X. D. Han, K. Zheng, Y. F. Zhang, X. N. Zhang, Z. Zhang and Z. L. Wang

      Article first published online: 17 JUL 2007 | DOI: 10.1002/adma.200602705

      Thumbnail image of graphical abstract

      The large-strain plasticity (LSP) of single-crystalline silicon nanowires (Si NWs) observed in situ at room temperature by axial tension experiments carried out in an ultrahigh-resolution electron microscope is reported. The LSP is demonstrated to result in a fourfold reduction in NW diameter before fracture (see figure), which is three orders of magnitude higher than that of bulk Si.

    12. Multicolor Emission on Prepatterned Substrates Using a Single Dye Species (pages 2119–2123)

      W. Hu, N. Lu, H. Zhang, Y. Wang, N. Kehagias, V. Reboud, C. M. Sotomayor Torres, J. Hao, W. Li, H. Fuchs and L. Chi

      Article first published online: 17 JUL 2007 | DOI: 10.1002/adma.200602491

      Thumbnail image of graphical abstract

      A new strategy for realizing patterned surfaces with different emission colors is demonstrated. This approach relies on the gas-phase deposition of dye molecules onto solid substrates that are prepatterned by nanoimprint lithography (see figure). Only a single molecular species is involved. Thus, the observed color change and corresponding spectral shift in the emission properties depends on the substrate used and can be tuned by surface engineering.

    13. Semiconductor Sub-Micro-/ Nanochannel Networks by Deterministic Layer Wrinkling (pages 2124–2128)

      Y. Mei, D. J. Thurmer, F. Cavallo, S. Kiravittaya and O. G. Schmidt

      Article first published online: 12 JUL 2007 | DOI: 10.1002/adma.200601622

      Thumbnail image of graphical abstract

      Semiconductor micro-/nanochannel networks are developed by deterministic layer wrinkling and applied into a fluidics study. Both linear (see figure) and circular nanochannel networks, consisting of a main channel and several perpendicularly oriented branch channels, are created, where the periodicity and position of the branch channels can be tuned and controlled by changing the width of the partially released layers and by applying appropriate lithography.

    14. Dual Nanoparticle/Substrate Control of Catalytic Dehydrogenation (pages 2129–2133)

      A. Y. Borisevich, S. Wang, S. N. Rashkeev, M. Glazoff, S. J. Pennycook and S. T. Pantelides

      Article first published online: 12 JUL 2007 | DOI: 10.1002/adma.200601618

      Thumbnail image of graphical abstract

      Chromia/alumina catalysts are widely used for oxidative dehydrogenation of alkanes, but questions about the relationship between their properties and characteristics remain. Experimental techniques and first-principles calculations are used to demonstrate that the reaction is enabled by CrOx clusters adsorbed on alumina surfaces, and that the key reaction sites are low-coordination-number O atoms (see figure).

    15. How (Ba0.5Sr0.5)(Fe0.8Zn0.2)O3–δ and (Ba0.5Sr0.5)(Co0.8Fe0.2)O3–δ Perovskites Form via an EDTA/Citric Acid Complexing Method (pages 2134–2140)

      J. Martynczuk, M. Arnold, H. Wang, J. Caro and A. Feldhoff

      Article first published online: 12 JUL 2007 | DOI: 10.1002/adma.200700322

      Thumbnail image of graphical abstract

      Perovskites with complex stoichiometries are widely synthesized by EDTA/citric acid complexing methods. Even though these methods are well established, details of the perovskite structure formation remained hidden. The structure analysis of different stages of the synthesis process allows the identification of the crystalline intermediates as spinel and carbonate. The perovskite is formed between them in a nanoscale solid-state reaction.

    16. High-Yield Synthesis of Rhombohedral Boron Nitride Triangular Nanoplates (pages 2141–2144)

      L. Q. Xu, J.   H. Zhan, J. Q. Hu, Y. Bando, X. L. Yuan, T. Sekiguchi, M. Mitome and D. Golberg

      Article first published online: 4 JUL 2007 | DOI: 10.1002/adma.200700366

      Thumbnail image of graphical abstract

      Unique, highly crystalline, triangular BN nanoplates (see figure) with a wide bandgap—which will ease their integration into nanoelectronic and photonic devices—are reported to be synthesized by reaction of NH4BF4 and NaNH2 with the assistance of metallic Ni. A thorough analysis of the morphological and structural characteristics of the nanoplates is presented.

    17. Enantioselective Sol–Gel Materials Obtained by Either Doping or Imprinting with a Chiral Surfactant (pages 2145–2150)

      S. Fireman-Shoresh, S. Marx and D. Avnir

      Article first published online: 12 JUL 2007 | DOI: 10.1002/adma.200601793

      Thumbnail image of graphical abstract

      Chiral pores are fabricated in phenylated sol–gel materials using chiral surfactants (see figure). The interactions between the pores with and without the surfactant and chiral molecular probes are investigated. The effect of entrapped and extracted surfactant changes the enantioselectivity of the material.

    18. Fabrication and Nanocompression Testing of Aligned Carbon-Nanotube–Polymer Nanocomposites (pages 2151–2156)

      E. J. García, A. J. Hart, B. L. Wardle and A. H. Slocum

      Article first published online: 12 JUL 2007 | DOI: 10.1002/adma.200700237

      Thumbnail image of graphical abstract

      The reinforcement of fiber–polymer composites with arrays of aligned carbon nanotubes (CNTs) is reported. Nanocomposite features containing vertically aligned CNTs and a commercially available polymer are fabricated and mechanically characterized with a direct nanocompression method using a flat punch mounted on a nanoindenter (see figure). The results show a reinforcement of 220 % at a CNT volume fraction of 2 %.

    19. Local Defectivity Control of 2D Self-Assembled Block Copolymer Patterns (pages 2157–2162)

      R. Ruiz, N. Ruiz, Y. Zhang, R. L. Sandstrom and C. T. Black

      Article first published online: 17 JUL 2007 | DOI: 10.1002/adma.200602470

      Thumbnail image of graphical abstract

      Surface patterning of copolymers via self-assembly is achieved by substrate design. The figure shows a polystyrene-block-poly(methyl methacrylate) symmetric diblock copolymer confined in a tapered structure. Engineering the channel structure provides local defectivity control for defect-free striped lamellar patterns at the nanometer scale.

    20. A Combined Top-Down/Bottom-Up Approach for the Nanoscale Patterning of Spin-Crossover Coordination Polymers (pages 2163–2167)

      G. Molnár, S. Cobo, J. A. Real, F. Carcenac, E. Daran, C. Vieu and A. Bousseksou

      Article first published online: 17 JUL 2007 | DOI: 10.1002/adma.200700448

      Thumbnail image of graphical abstract

      Micro- and nanometer-sized patterns of the spin-crossover compound Fe(pyrazine)[Pt(CN)4] have been fabricated using a combination of lift-off and multilayer sequential assembly methods. These patterns (see figure and inside cover) exhibit a bistability of their electronic states and, thus, represent a novel platform for a wide array of potential applications.

    21. Weak Epitaxy Growth Affording High-Mobility Thin Films of Disk-Like Organic Semiconductors (pages 2168–2171)

      H. Wang, F. Zhu, J. Yang, Y. Geng and D. Yan

      Article first published online: 20 JUL 2007 | DOI: 10.1002/adma.200602566

      Thumbnail image of graphical abstract

      Thin films of phthalocyanine compounds show weak epitaxial growth on a monodomain film of a rod-like molecule (see figure). The resulting organic electronic devices exhibit high charge carrier mobilities close to those of the single-crystal devices.

    22. Necklace-like Noble-Metal Hollow Nanoparticle Chains: Synthesis and Tunable Optical Properties (pages 2172–2176)

      J. Zeng, J. Huang, W. Lu, X. Wang, B. Wang, S. Zhang and J. Hou

      Article first published online: 20 JUL 2007 | DOI: 10.1002/adma.200602440

      Thumbnail image of graphical abstract

      Tunable fabrication of noble-metal hollow nanoparticle chains (HNPCs) is achieved by a strategy that exploits the variation of an external applied magnetic field during synthesis (see figure). The magnitude of the field has a strong effect on the nanoparticles assembly, ranging from disperse to chainlike. The length and the optical properties of the HNPCs can be tuned, and such a synthesis may provide enhanced functionality for applications such as drug delivery or catalysis.

  6. Index

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Review
    6. Communications
    7. Index
    1. Author Index and Subject Index Adv. Mater. 16/2007 (pages 2177–2178)

      Article first published online: 14 AUG 2007 | DOI: 10.1002/adma.200790058

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