Advanced Materials

Cover image for Vol. 22 Issue 21

June 4, 2010

Volume 22, Issue 21

Pages 2279–2380

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Review
    6. Communications
    1. Superhydrophobic Coatings: The Salvinia Paradox: Superhydrophobic Surfaces with Hydrophilic Pins for Air Retention Under Water (Adv. Mater. 21/2010)

      Wilhelm Barthlott, Thomas Schimmel, Sabine Wiersch, Kerstin Koch, Martin Brede, Matthias Barczewski, Stefan Walheim, Aaron Weis, Anke Kaltenmaier, Alfred Leder and Holger F. Bohn

      Article first published online: 31 MAY 2010 | DOI: 10.1002/adma.201090075

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      The cover shows the sophisticated surface design of the floating water fern Salvinia. The unique surface architecture is composed of complex hydrophobic eggbeater-shaped hairs with hydrophilic terminal cells. The evenly distributed hydrophilic patches stabilize the air layer by pinning the air/water interface in place. The paradox combination of hydrophilic patches on superhydrophobic surfaces (the “Salvinia Effect”) provides an innovative concept for smart biomimetic surfaces in maritime coatings and underwater applications, as reported by Wilhelm Barthlott, Thomas Schimmel, and co-workers on p. 2325. Cover: © Martin Oeggerli / www.Micronaut.ch, original SEM scan by Prof. Barthlott.

  2. Inside Front Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Review
    6. Communications
    1. Nanofabrication: Curving Nanostructures Using Extrinsic Stress (Adv. Mater. 21/2010)

      Jeong-Hyun Cho, Teena James and David H. Gracias

      Article first published online: 31 MAY 2010 | DOI: 10.1002/adma.201090076

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      A simple way to fabricate simultaneously patterned and curved nanostructures with radii as small as 20 nm is demonstrated on p. 2320 by David Gracias and co-workers. Curved nanostructures with both homogeneous (nanorings, nanotubes) and variable (nanospirals) radii of curvature spontaneously assembled when grain coalescence was induced in electron-beam-patterned thin-film bilayers. In addition, large stresses could be induced after deposition and patterning and only when required, thereby suggesting an extrinsic stress-based strategy to trigger assembly on demand.

  3. Contents

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Review
    6. Communications
    1. Contents: (Adv. Mater. 21/2010) (pages 2279–2284)

      Article first published online: 31 MAY 2010 | DOI: 10.1002/adma.201090077

  4. Review

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Review
    6. Communications
    1. Aligned, Ultralong Single-Walled Carbon Nanotubes: From Synthesis, Sorting, to Electronic Devices (pages 2285–2310)

      Zhongfan Liu, Liying Jiao, Yagang Yao, Xiaojun Xian and Jin Zhang

      Article first published online: 31 MAR 2010 | DOI: 10.1002/adma.200904167

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      Aligned, ultralong single-walled carbon nanotubes represent attractive building blocks for nanoelectronics. The structural uniformity along the tube axis and well-ordered two-dimensional architectures on a wafer surface may provide a straightforward platform for fabricating high-performance SWNT-based integrated circuits. We summarize the recent advances in synthesis, identification, device fabrication and integration of aligned, ultralong SWNTs together with a discussion on the major challenges and opportunities for practical applications.

  5. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Contents
    5. Review
    6. Communications
    1. Quantum Confinement in Self-Assembled Bioinspired Peptide Hydrogels (pages 2311–2315)

      Nadav Amdursky, Ehud Gazit and Gil Rosenman

      Article first published online: 20 MAY 2010 | DOI: 10.1002/adma.200904034

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      The self-assembly process of peptide fibrils is followed by spectroscopic measurements, which show that a quantum confinement (QC) nanocrystal structure is formed within the peptide fibrils as they assemble into a hydrogel. The optical and electronic properties of this first bioorganic-inspired QC structure (see figure) are demonstrated to be related to the QC effect.

    2. Composite Holographic Gratings Containing Light-Responsive Liquid Crystals for Visible Bichromatic Switching (pages 2316–2319)

      Luciano De Sio, Svetlana Serak, Nelson Tabiryan, Sameh Ferjani, Alessandro Veltri and Cesare Umeton

      Article first published online: 7 APR 2010 | DOI: 10.1002/adma.200903838

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      Polymeric microstructures, produced in a multi-step chemico-physical process, confine and stabilize a well-aligned nematic liquid crystal (NLC) film, which is doped with a high-performance mesogenic azobenzene dye, sensitive in the visible range.

    3. Curving Nanostructures Using Extrinsic Stress (pages 2320–2324)

      Jeong-Hyun Cho, Teena James and David H. Gracias

      Article first published online: 7 APR 2010 | DOI: 10.1002/adma.200904410

      Thumbnail image of graphical abstract

      We demonstrate the concept of inducing stresses in thin films post-deposition (extrinsic stress) to curve nanostructures on demand. The remarkably high extrinsic stress, induced by triggering grain coalescence in Sn thin films, was used to self]assemble 3D nanostructures with radii of curvature as small as 20 nm. The fabrication methodology required only simple processing steps and the self]assembly process was highly parallel. Curved nanostructures with any desired pattern and both homogeneous (rings, tubes) and variable radii of curvature (spirals, talons) could be constructed.

    4. The Salvinia Paradox: Superhydrophobic Surfaces with Hydrophilic Pins for Air Retention Under Water (pages 2325–2328)

      Wilhelm Barthlott, Thomas Schimmel, Sabine Wiersch, Kerstin Koch, Martin Brede, Matthias Barczewski, Stefan Walheim, Aaron Weis, Anke Kaltenmaier, Alfred Leder and Holger F. Bohn

      Article first published online: 28 APR 2010 | DOI: 10.1002/adma.200904411

      Thumbnail image of graphical abstract

      A novel mechanism for long-term air retention under water is found in the sophisticated surface design of the water fern Salvinia. Its floating leaves are evenly covered with complex hydrophobic hairs retaining a layer of air when submerged under water. Surprisingly the terminal cells of the hairs are hydrophilic. These hydrophilic patches stabilize the air layer by pinning the air–water interface. This “Salvinia Effect” provides an innovative concept to develop biomimetic surfaces with long-term air-retention capabilities for under water applications. © Martin Oeggerli / www.Micronaut.ch, original SEM scan by Prof. Barthlott.

    5. Effect of an Ultrathin TiO2 Layer Coated on Submicrometer-Sized ZnO Nanocrystallite Aggregates by Atomic Layer Deposition on the Performance of Dye-Sensitized Solar Cells (pages 2329–2332)

      Kwangsuk Park, Qifeng Zhang, Betzaida Battalla Garcia, Xiaoyuan Zhou, Yoon-Ha Jeong and Guozhong Cao

      Article first published online: 7 APR 2010 | DOI: 10.1002/adma.200903219

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      An ultrathin TiO2 layer is successfully coated on the surface of sub-m-sized aggregates of ZnO nanocrystallites through the atomic layer deposition (ALD) technique. The ZnO core/TiO2 shell structure increases the open-circuit voltage, without impairing the photocurrent density and results in an increased power conversion efficiency from 5.2% to 6.3%.

    6. High-Performance Flexible Transparent Thin-Film Transistors Using a Hybrid Gate Dielectric and an Amorphous Zinc Indium Tin Oxide Channel (pages 2333–2337)

      Jun Liu, D. Bruce Buchholz, Robert P. H. Chang, Antonio Facchetti and Tobin J. Marks

      Article first published online: 20 MAY 2010 | DOI: 10.1002/adma.200903761

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      High-performance flexible transparent thin-film transistors (TFTs) are demonstrated using amorphous zink indium tin oxide (ZITO) transparent oxide conductor electrodes, an amorphous ZITO transparent oxide semiconductor channel, and a vapor-deposited self-assembled nanodielectric (v-SAND) gate insulator. These TFTs exhibit a large field-effect mobility of 110 cm2V−1s−1, a current on/off ratio of 104, and a low operating voltage of 1.0 V, along with very good optical transparency and mechanical flexibility.

    7. Near-Bulk Conductivity of Gold Nanowires as Nanoscale Interconnects and the Role of Atomically Smooth Interface (pages 2338–2342)

      Kevin Critchley, Bishnu P. Khanal, Marcin Ł. Górzny, Leonid Vigderman, Stephen D. Evans, Eugene R. Zubarev and Nicholas A. Kotov

      Article first published online: 7 APR 2010 | DOI: 10.1002/adma.201000236

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      Atomically smooth gold nanowires with high aspect ratios are grown using the seeded growth process. This allows control of the diameter of the nanowires to a high degree of precision. Two and four-probe nanoscale transport measurements reveal that the nanowires have low resistivity. Only a small increase in resistivity is observed between diameters of 29 nm and 185 nm suggesting that surface scattering is only a small contribution.

    8. Chemical Nanosensors Based on Composite Molecularly Imprinted Polymer Particles and Surface-Enhanced Raman Scattering (pages 2343–2348)

      Marc Bompart, Yannick De Wilde and Karsten Haupt

      Article first published online: 30 MAR 2010 | DOI: 10.1002/adma.200904442

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      Chemical nanosensors with a submicrometer core–shell composite design, based on a polymer core, a molecularly imprinted polymer (MIP) shell for specific analyte recognition, and an interlayer of gold nanoparticles for signal amplification, are described. SERS measurements on single nanosensors yield detection limits of 10−7 M for the β-blocker propranolol, several orders of magnitude lower than on plain MIP spheres.

    9. Induced Sensitivity and Selectivity in Thin-Film Transistor Sensors via Calixarene Layers (pages 2349–2353)

      Anatoliy N. Sokolov, Mark E. Roberts, Olasupo B. Johnson, Yadong Cao and Zhenan Bao

      Article first published online: 7 APR 2010 | DOI: 10.1002/adma.200903305

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      Sensors based on organic field-effect transistors (OFETs) must overcome challenges in reproducibility, sensitivity, and selectivity. Here we describe an approach to increase the sensitivity and induce selectivity within an existing (OFET) through the incorporation of an evaporated sensor layer based on a calix[n]arene molecule. The mild method does not influence device properties, and is amendable to incorporation into reproducible, commercial transistors.

    10. Advanced Optical Metamaterials (pages 2354–2357)

      Thomas Paul, Christoph Menzel, Carsten Rockstuhl and Falk Lederer

      Article first published online: 29 MAR 2010 | DOI: 10.1002/adma.200903865

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      A new class of bulk metamaterials is proposed, which are assembled of functional layers with differing layout properties, as shown in the figure. These enhanced degrees of freedom allow to design metamaterials, which perform optically in a predefined manner. We apply this approach to design isotropic metamaterials and metamaterials in which light propagates free of diffraction.

    11. Nanotemplating of Biodegradable Polymer Membranes for Constant-Rate Drug Delivery (pages 2358–2362)

      Daniel A. Bernards and Tejal A. Desai

      Article first published online: 7 APR 2010 | DOI: 10.1002/adma.200903439

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      A nanoporous biodegradable polymer (polycaprolactone) is fabricated utilizing a zinc oxide nanotemplate (see figure). Chemical characterization verifies removal of the template, and preliminary tests on the cytotoxicity demonstrate basic biocompatibility. Diffusion of a model small molecule and a protein are shown to be first and zero order, respectively, indicating these nanoporous membranes may be useful for controlled release of protein-based therapeutics.

    12. Rhombicuboctahedral Three-Dimensional Photonic Quasicrystals (pages 2363–2366)

      Alexandra Ledermann, Martin Wegener and Georg von Freymann

      Article first published online: 6 APR 2010 | DOI: 10.1002/adma.200903885

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      The aesthetics of quasicrystals has fascinated mankind already for centuries. Numerous examples are known in one and two dimensions, yet in three dimensions only icosahedral quasicrystals have been realized and observed to date in any system, i.e., in man-made, natural, photonic, and phononic quasicrystals. We rationally construct the novel class of three-dimensional rhombicuboctahedral quasicrystals and realize it as polymer microstructure.

    13. High-Performance Oxygen-Permeable Membranes with an Asymmetric Structure Using Ba0.95La0.05FeO3−δ Perovskite-Type Oxide (pages 2367–2370)

      Ken Watenabe, Masayoshi Yuasa, Tetsuya Kida, Yasutake Teraoka, Noboru Yamazoe and Kengo Shimanoe

      Article first published online: 30 MAR 2010 | DOI: 10.1002/adma.200903953

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      High oxygen permeability was achieved using an asymmetric Ba0.95La0.05FeO3−δ membrane. In this membrane, oxygen diffuses physically through pores of a porous support and oxygen permeates electrochemically through a dense layer. The oxygen permeation flux of the asymmetric Ba0.95La0.05FeO3−δ membrane reached more than 10 cm3 (STP) min−1 cm−2 from a test gas containing 50% oxygen at 930 °C.

    14. High Mobility Ambipolar Charge Transport in Polyselenophene Conjugated Polymers (pages 2371–2375)

      Zhuoying Chen, Henrik Lemke, Sebastian Albert-Seifried, Mario Caironi, Martin Meedom Nielsen, Martin Heeney, Weimin Zhang, Iain McCulloch and Henning Sirringhaus

      Article first published online: 29 MAR 2010 | DOI: 10.1002/adma.200903711

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      High mobility ambipolor polymer field-effect transistors based on a series of regioregular polyselenophenes are presented together with their morphological and optical properties. Balanced electron and hole mobilities on the order of 0.03 cm2 V−1 s−1 are observed by employing a simple top-gate/bottom-contact configuration with photolithographically defined gold source/drain contacts. High gain complementary-like voltage inverters are demonstrated based on two identical ambipolar transistors.

    15. ZnS Branched Architectures as Optoelectronic Devices and Field Emitters (pages 2376–2380)

      Zhi-Gang Chen, Lina Cheng, Hong-Yi Xu, Ji-Zi Liu, Jin Zou, Takashi Sekiguchi, Gao Qing (Max) Lu and Hui-Ming Cheng

      Article first published online: 29 APR 2010 | DOI: 10.1002/adma.200903643

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      A unique ZnS branched architecture was fabricated by a facile thermal evaporation method. Stable UV emission at 327 nm and superior field emission with a low turn-on field, a high field-enhancement factor, a large current density, and small fluctuation were observed.

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