Advanced Materials

Cover image for Advanced Materials

January, 2004

Volume 16, Issue 1

Pages 3–98

    1. Contents: Adv. Mater. 1/2004 (pages 3–10)

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200490001

    2. A Fresh Look at Materials Science (page 15)

      E. Levy

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200490000

      2004 has brought a fresh look to Advanced Materials. This editorial highlights the improvements made to the layout of the journal as well as other events you can look forward to this year.

    3. Peptide and Protein Presenting Materials for Tissue Engineering (pages 17–25)

      Y. Hirano and D. J. Mooney

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200300383

      Successful regeneration of complex tissue structures, such as the engineered bone–cartilage interface shown in the Figure, will likely depend on the design and synthesis of materials presenting appropriate signals to interacting cells. An overview of current techniques to present cell-interactive proteins and peptides from materials is provided, along with demonstrations of their utility.

    4. Emulsion-Templated Gold Beads Using Gold Nanoparticles as Building Blocks (pages 27–30)

      H. Zhang, I. Hussain, M. Brust and A. I. Cooper

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200306153

      Highly porous gold beads have been synthesized from gold nanoparticle “building blocks” using emulsion- templated polymer beads as scaffolds (see Figure and cover for scanning electron microscopy images). The distribution of the nanoparticles throughout the scaffold can be controlled, which in turn allows a variety of complex structures to be produced.

    5. Micropixelated Luminescent Nanocrystal Arrays Synthesized by Ion Implantation (pages 31–34)

      A. Meldrum, K. S. Buchanan, A. Hryciw and C. W. White

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200305694

      It is shown that a simple lithographic method can result in single- or two- color “micropixelated” arrays of luminescent silicon nanoparticles. Other colors should be readily possible. This combined spatial and color control may be important with respect to future applications of these highly luminescent nanocrystalline materials. The Figure shows a fluorescence image of a patterned nanocrystal array.

    6. In-Situ Growth of “Fused”, Ozonized Single-Walled Carbon Nanotubes—CdTe Quantum Dot Junctions (pages 34–37)

      S. Banerjee and S. S. Wong

      Version of Record online: 16 OCT 2003 | DOI: 10.1002/adma.200305661

      A molecular-scale interface, consisting of a “fused” heterojunction between a nanotube and a quantum dot, has been prepared. This work is significant for the construction of functional hierarchical assemblies with unique properties. The Figure shows a schematic representation of a CdTe quantum dot grown directly onto the oxygenated surface of an ozonized single-walled carbon nanotube template (see also inside cover).

    7. Indium-Assisted Growth of Aligned Ultra-Long Silica Nanotubes (pages 37–40)

      Y. Li, Y. Bando and D. Golberg

      Version of Record online: 16 OCT 2003 | DOI: 10.1002/adma.200305732

      Well-aligned silica nanotubes with lengths up to 0.9–1.0 mm have been prepared via a vapor–liquid–solid process. The nanotubes are either partially filled with indium or hollow (see Figure). The thermal expansion behavior of a liquid indium column inside a silica nanotube, a prospective novel inorganic nanotube-based nanothermometer, is analyzed in a transmission electron microscope.

    8. Nanobelt-Templated Growth of Carbon Nanotube Rows (pages 40–44)

      A. Cao, G. Meng and P. M. Ajayan

      Version of Record online: 11 NOV 2003 | DOI: 10.1002/adma.200305667

      Rows of aligned carbon nanotubes standing shoulder by shoulder (see Figure) have been synthesized by growing nanotubes inside Au micro- and nanotrenches created by nanobelts or nanowires. This simple non-lithographic method can be used to fabricate nanotube rows with a width of less than 2 μm, and a length over hundreds of micrometers.

    9. Demonstration of Flexible Freestanding All-Polymer Integrated Optical Ring Resonator Devices (pages 44–48)

      Y. Huang, G. T. Paloczi, J. K. S. Poon and A. Yariv

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200305813

      A simple method to fabricate thin freestanding all-polymer integrated optical devices and the transfer of the devices to various substrates, such as the curved surfaces of capillary tubes, is reported. A passive microring resonator optical filter device (see Figure) with a –27 dB notch extinction for wavelengths in the telecommunication band, which is within the range of requirements for practical telecommunications applications, is also shown.

    10. Giant Coercive Field of Nanometer- Sized Iron Oxide (pages 48–51)

      J. Jin, S. Ohkoshi and K. Hashimoto

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200305297

      Nanocrystals of iron oxide in a silica matrix exhibiting a giant Hc value of 2.0 T at room temperature are reported. The nanocomposite was obtained by combining reverse-micelle and sol–gel methods. The nanocrystals of iron oxide are composed of the ϵ-Fe2O3 phase, with rod-like particles 100–140 nm long and 20–40 nm wide. The Figure shows the hysteresis curve of the nanocrystals.

    11. Laser-Induced Thermal Imaging of Polymer Light-Emitting Materials on Poly(3,4-ethylenedioxythiophene): Silane Hole-Transport Layer (pages 51–54)

      J. Y. Lee and S. T. Lee

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200305699

      The addition of methacryloxypropyltrimethoxysilane to poly(3,4- ethylenedioxythiophene) has enabled laser-induced thermal imaging (LITI) of polymer light-emitting materials on a hole-transport layer (see Figure for example). The IVL (current–voltage–luminance) performances of the device patterned by the LITI process are comparable to those of typical spin-coated devices.

    12. Nanoporous Ultra-Low-κ Films Prepared from Fluorinated Polyimide with Grafted Poly(acrylic acid) Side Chains (pages 54–57)

      W.-C. Wang, R. H. Vora, E.-T. Kang, K.-G. Neoh, C.-K. Ong and L.-F. Chen

      Version of Record online: 16 OCT 2003 | DOI: 10.1002/adma.200305185

      Thermal decomposition of labile poly(acrylic acid) (PAAc) side chains grafted onto fluorinated polyimide backbones (see Figure) is used to prepare nanoporous ultra-low-κ fluorinated polyimide films. The dielectric constant of the nanoporous fluorinated polyimide film can be varied by altering the graft concentration of the labile side chains.

    13. Polyacrylonitrile Single-Walled Carbon Nanotube Composite Fibers (pages 58–61)

      T. V. Sreekumar, T. Liu, B. G. Min, H. Guo, S. Kumar, R. H. Hauge and R. E. Smalley

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200305456

      Polyacrylonitrile (PAN) fibers containing 10 wt.-% single-walled carbon nanotubes (SWNTs) exhibit a 100 % improvement in tensile modulus and reduced thermal shrinkage and polymer solubility. A 40 °C increase in glass transition temperature as compared to the control PAN fiber is also observed (see Figure). SWNT anisotropy has been observed using infrared spectroscopy.

    14. Efficient Organic Blue-Light-Emitting Devices with Double Confinement on Terfluorenes with Ambipolar Carrier Transport Properties (pages 61–65)

      C.-C. Wu, Y.-T. Lin, K.-T. Wong, R.-T. Chen and Y.-Y. Chien

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200305619

      Ter(9,9-diarylfluorene)s (TDAFs) exhibit many intriguing properties promising for blue light-emitting devices, such as high thin-film photoluminescence quantum yields (∼ 90 %), high glass-transition temperatures (> 200 °C), and an unusual ambipolar carrier-transport capability. Successful implementation of a double- heterostructure device configuration that provides effective confinement of both carriers and excitons in TDAFs results in an electroluminescence performance (5.3 % external quantum efficiency) promising for application in blue-emitting devices.

    15. Self-Assembled In2O3 Nanocrystal Chains and Nanowire Networks (pages 65–69)

      J. Y. Lao, J. Y. Huang, D. Z. Wang and Z. F. Ren

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200305684

      The synthesis of self-assembled In2O3 nanocrystal chains and networks (see Figure) on SiO2-covered Si substrates by a thermal evaporation and condensation method is reported. Au catalyst is required for the growth. The chains and networks can be used for the fabrication of complex nanoelectronic devices and toward a better understanding of nanodevice physics.

    16. Carbon Nanotubes on Carbon Nanofibers: A Novel Structure Based on Electrospun Polymer Nanofibers (pages 69–73)

      H. Hou and D. H. Reneker

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200306205

      Electrospun nanofibers of polyacrylonitrile, containing an iron compound, have been converted to carbon nanofibers, with iron particles on their surfaces. The iron particles catalyze the growth of carbon nanotubes with iron tips (see Figure). A mechanically strong and electrically conducting path exists between each metal particle and the supporting nanofiber network, which extends to macroscopic dimensions.

    17. Fabrication of Large-Area Silicon Nanowire p–n Junction Diode Arrays (pages 73–76)

      K. Q. Peng, Z. P. Huang and J. Zhu

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200306185

      Large-area silicon nanowire p–n junction diode arrays (see Figure) have been fabricated by chemical etching of planar silicon p–n junction wafers in aqueous HF solution that contains appropriate amounts of silver nitrate near room temperature. The I–V characteristics have been measured using current-sensing atomic force microscopy, and nonlinear and rectifying electrical transport behavior has been observed.

    18. Electric Field Singularity Assisted Nanopatterning (pages 76–80)

      N. Ravishankar, V. B. Shenoy and C. B. Carter

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200305337

      Ordered arrays of Pt nanoparticles (see Figure) have been produced on a reconstructed alumina surface that serves as a template for nanopatterning. The Pt particles condense from an undersaturated vapor phase only along the crest regions on the reconstructed plane. It is shown that the presence of an electric field singularity leads at the crest regions to the highly site-specific formation of nanoparticles.

    19. Patterning Colloidal Crystals by Lift-up Soft Lithography (pages 81–84)

      J. Yao, X. Yan, G. Lu, K. Zhang, X. Chen, L. Jiang and B. Yang

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200306150

      Patterned colloidal crystals have been fabricated by a lift-up soft lithography method based on the selective transfer of a single layer of close-packed microspheres from the crystal film to the protruding surface of a poly(dimethylsiloxane) stamp. The Figure shows a scanning electron microscopy image of the ordered square array in the top layer of a 3D colloidal crystal that was produced using a two-step lift-up process.

    20. Carbon Nanotube/CdS Core–Shell Nanowires Prepared by a Simple Room-Temperature Chemical Reduction Method (pages 84–87)

      J. Cao, J.-Z. Sun, J. Hong, H.-Y. Li, H.-Z. Chen and M. Wang

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200306100

      A facile solution-phase reaction has been developed to fabricate carbon nanotube/CdS core–shell nanowires (see Figure). The thickness of the CdS sheath can be controlled by varying the concentration of the precursors. The obtained heterostructures demonstrate an enhanced surface photovoltage response, which is associated with the efficient photoinduced charge transfer from the CdS shell to the carbon nanotube core.

    21. Electroluminescence in n-ZnO Nanorod Arrays Vertically Grown on p-GaN (pages 87–90)

      W. I. Park and G.-C. Yi

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200305729

      Electroluminescent (EL) devices (see Figure) have been fabricated using n-ZnO nanorod arrays grown on p-GaN epilayers. Simple heteroepitaxial growth yields vertically aligned ZnO nanorods with an abrupt interface on GaN. The p–n heterojunction EL device shows a high current density and strong electroluminescence even at a reverse-bias voltage of 3 V.

    22. Preparation of Arrays of Isolated Spherical Cavities by Self-Assembly of Polystyrene Spheres on Self-Assembled Pre-patterned Macroporous Films (pages 90–93)

      M. E. Abdelsalam, P. N. Bartlett, J. J. Baumberg and S. Coyle

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200306052

      Isolated metallic arrays of spherical cavities (see Figure) have been prepared using a simple scheme that combines two self-assembly steps using monodisperse polystyrene spheres of two different sizes and electrochemical deposition. The ability to easily fabricate, at low cost, a large variety of such photonic metallic structures promises applicability in many diverse areas, ranging from biotechnology to optoelectronics.

    23. SiC–SiO2–C Coaxial Nanocables and Chains of Carbon Nanotube–SiC Heterojunctions (pages 93–96)

      Y. Li, Y. Bando and D. Golberg

      Version of Record online: 16 JAN 2004 | DOI: 10.1002/adma.200306117

      Coaxial nanocables composed of a uniform single-crystalline β-SiC core, an amorphous SiO2 intermediate layer, and a graphitic carbon sheath (see Figure) have been synthesized via a simple chemical vapor deposition route. By annealing the nanocables, chains of carbon nanotube–SiC heterojunctions have been prepared. These nanostructures are suggested to be highly valuable as building blocks for nanoscale electronic devices.