Advanced Materials

Cover image for Advanced Materials

October, 2003

Volume 15, Issue 19

Pages 1573–1660

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    2. Block Copolymers as a Tool for Nanomaterial Fabrication (pages 1583–1594)

      M. Lazzari and M.A. López-Quintela

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200300382

      Self-assembled block copolymers (BCs) have become one of the most promising tools for the fabrication of nanomaterials. Their potential for technological applications and for the preparation of model objects is highlighted here (the Figure shows some of the most exploited mesostructures). The use of BCs as nanostructured materials and nanomaterial fabrication via template formation are discussed.

    3. Surface-Enhanced Raman Scattering of Small Molecules from Silver-Coated Silicon Nanopores (pages 1595–1598)

      S. Chan, S. Kwon, T.-W. Koo, L.P. Lee and A.A. Berlin

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305149

      New ways of detecting low concentrations of analytes, which could be used as part of integrated on-chip devices, are offered by surface-enhanced Raman-scattering substrates fabricated on the nanoscale. The ability of metal surfaces to amplify a Raman-scattering signal (see Figure) is combined with an enlarged substrate surface area, allowing orders of magnitude enhancement for the detection of rhodamine 6G and adenine.

    4. Templated Self-Assembly of Block Copolymers: Effect of Substrate Topography (pages 1599–1602)

      J.Y. Cheng, C.A. Ross, E.L. Thomas, H.I. Smith and G.J. Vancso

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305244

      Topographical confinement is used to template the formation of nanoscale domains in a self-assembled block copolymer film. The topographical template controls the row spacings and feature dimensions of the copolymer and can deliberately introduce defects in the arrays (see Figure). For example, a sharp edge feature leads to a missing domain and pins the lateral position of the polymer array. (See also inside cover.)

    5. Synthesis of Ordered Mesoporous Carbon with Bimodal Pore System and High Pore Volume (pages 1602–1606)

      A.-H. Lu, W. Schmidt, B. Spliethoff and F. Schüth

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305176

      Ordered mesoporous carbon, named as NCC-1, has been synthesized via a nanocasting process using SBA-15 as the template and diluted furfuryl alcohol solution as the carbon source. NCC-1 shows a bimodal pore size distribution (see Figure) in the mesopore range and a high pore volume up to 3.2 cm3 g–1. Since the pore systems are independently generated at different stages during the synthesis, they can also be modified independently.

    6. Reversible Switching Between Optically Isotropic and Birefringent States in a Bent-Core Liquid Crystal (pages 1606–1610)

      A. Jákli, Y.-M. Huang, K. Fodor-Csorba, A. Vajda, G. Galli, S. Diele and G. Pelzl

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305379

      The tilted smectic liquid-crystal phase of an ester-based bent-core mesogen (see Figure) is optically isotropic due to the combination of suitable tilt and opening angles of the bent cores. In electric fields, V-shaped switching between isotropic and birefringent states is observed. Both the antiferroelectric and ferroelectric states consist of optically active domains due to the twisted molecular structure.

    7. Nanoporous Structures Prepared by an Electrochemical Deposition Process (pages 1610–1614)

      H.-C. Shin, J. Dong and M. Liu

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305160

      Free-standing metal foam structures with nano-dendritic walls of copper and tin are fabricated by an electrochemical deposition process. This unique structure is attributed to the concurrent generation of hydrogen bubbles with extremely fast metal deposition at high cathodic current densities. The Figure shows a typical example of the foam-like structure of tin deposits with walls composed of nano-dendritic branches.

    8. Tailoring Discotic Mesophases: Columnar Order Enforced with Hydrogen Bonds (pages 1614–1618)

      R.I. Gearba, M. Lehmann, J. Levin, D.A. Ivanov, M.H.J. Koch, J. Barberá, M.G. Debije, J. Piris and Y.H. Geerts

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305137

      Hydrogen bonding can be used to significantly enforce the intra-columnar stacking order in discotic mesogens. The ordered hexagonal columnar mesophase of a HAT-CONHR derivative is characterized by the smallest inter-disk distance ever found in columnar liquid crystals (3.18–3.20 Å). This additional attractive interaction between the disks in the column results in a regular disc stacking and thus in a high charge-carrier mobility over the whole investigated temperature range (from room temperature up to 200 °C).

    9. Efficient Field Emission from Highly Aligned, Graphitic Nanotubes Embedded with Gold Nanoparticles (pages 1618–1622)

      K. Kim, S.H. Lee, W. Yi, J. Kim, J.W. Choi, Y. Park and J.-I. Jin

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305242

      By utilizing highly aligned graphitic nanotubes embedded with gold nanoparticles an efficient field-emission device can be constructed. These have been synthesized by first preparing composite nanotubes consisting of poly(p-phenylenevinylene) and Au nanoparticles by chemical vapor deposition polymerization, followed by carbonization. The Figure shows transmission electron microscopy images of these nanotubes.

    10. High Coercive Field for Nanoparticles of CoFe2O4 in Amorphous Silica Sol–Gel (pages 1622–1625)

      A. Hutlova, D. Niznansky, J.-L. Rehspringer, C. Estournès and M. Kurmoo

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305305

      Unusually high magnetic hardness, characterized by a coercive field of 2 T at 2 K, has been observed for 12 nm particles of CoFe2O4 (15%) in amorphous silica prepared by the sol–gel technique and sintered at 1000 °C. Field- and temperature-dependence magnetization data (see Figure) for these particles and those of 3.2 nm suggest that dipolar interaction between particles is responsible for this enhancement.

    11. Novel Ferroelectric Polymer Composites with High Dielectric Constants (pages 1625–1629)

      Z.-M. Dang, Y.-H. Lin and C.-W. Nan

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200304911

      A very simple blending and hot-molding technique has been used to prepare novel ferroelectric polymer composites of poly(vinylidene fluoride) (PVDF) and Ni (see Figure) with a high dielectric constant of weak frequency- and temperature-dependence. The polymer composites are flexible and of low dielectric loss. The electrical behavior observed in such composites can be described well using percolation theory.

    12. Morphological Control of Tapered and Multi-Junctioned Carbon Tubular Structures (pages 1629–1632)

      G. Bhimarasetti, M.K. Sunkara, U.M. Graham, B.H. Davis, C. Suh and K. Rajan

      Version of Record online: 25 AUG 2003 | DOI: 10.1002/adma.200305400

      Thin walled, carbon tubular structures (see Figure and also cover) with varying inner diameters in the form of nozzles, straight tubes, tube-on-cones, and funnels have been synthesized by in-situ control of gallium-carbon wetting behavior using gas phase chemistry. In addition, carbon tubular structures with large internal diameters have been coalesced during growth to create Y-junctions suitable for micro/nano-fluidic applications.

    13. 30 nm Channel Length Pentacene Transistors (pages 1632–1635)

      Y. Zhang, J.R. Petta, S. Ambily, Y. Shen, D.C. Ralph and G.G. Malliaras

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305158

      Advances in sample fabrication have allowed the fabrication of pentacene transistors with channel lengths down to 30 nm. The Figure shows a transistor with a channel length and width of 27 nm and 130 nm, respectively. Graceful scaling of the current–voltage characteristics as a function of channel length and width is demonstrated.

    14. Highly Efficient and Thermally Stable Electro-optic Polymer from a Smartly Controlled Crosslinking Process (pages 1635–1638)

      J. Luo, M. Haller, H. Li, T.-D. Kim and A.K.-Y. Jen

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305202

      A nonlinear optical polymer, which is thermoreversibly crosslinkable (see Figure), has been developed to overcome the nonlinearity–stability trade-off in poled polymers. High poling efficiency has been achieved after controlled, mild lattice hardening via the Diels–Alder crosslinking reaction. The resulting material exhibits a large electro-optic coefficient (r33 = 76 pm V–1 at 1.3 μm) and excellent temporal stability.

    15. Nanoparticle Inks for Directed Assembly of Three-Dimensional Periodic Structures (pages 1639–1643)

      Q. Li and J.A. Lewis

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305413

      Colloidal inks, comprised of concentrated barium titanate nanoparticle gels, were directly assembled via a robotically controlled deposition technique. 3D periodic lattices were created through layer-by-layer patterning of parallel rods, whose periodicity far exceeded the dimension of the nanoparticle building blocks. The Figure shows a scanning electron microscopy image of a 3D periodic lattice (top view).

    16. Self-Assembled Electroluminescent Polymers Derived from Terpyridine-Based Moieties (pages 1643–1647)

      S.-C. Yu, C.-C. Kwok, W.-K. Chan and C.-M. Che

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305002

      A family of self-assembled zinc terpyridyl polymers that exhibit emission colors ranging from violet to yellow (see Figure) with high photoluminescence (PL) quantum yields has been developed. These polymers are promising light-emitting materials for electroluminescent (EL) devices, and the EL of the Zn terpyridyl polymer in the blue region is particularly desirable.

      Corrected by:

      Correction: Self-Assembled Electroluminescent Polymers Derived from Terpyridine-Based Moieties

      Vol. 18, Issue 2, 246, Version of Record online: 11 JAN 2006

    17. Synthesis of Hierarchical Superstructures Consisting of BaCrO4 Nanobelts in Catanionic Reverse Micelles (pages 1647–1651)

      H. Shi, L. Qi, J. Ma, H. Cheng and B. Zhu

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305625

      A variety of novel BaCrO4 nanostructures, such as nanobelts and their tree-like superstructures (see Figure), have been synthesized in a unique catanionic reverse micelle system by simply changing the mixing ratio between the anionic and cationic surfactants. This synthetic method provides a simple, novel method for direct assembly of inorganic nanobelts into hierarchical superstructures.

    18. Ultralong, Well-Aligned Single-Walled Carbon Nanotube Architectureson Surfaces (pages 1651–1655)

      S. Huang, B. Maynor, X. Cai and J. Liu

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305203

      A novel fast-heating chemical vapor deposition (CVD) method to grow ultralong, well-aligned single-walled carbon nanotubes (SWNTs) is developed. The control of lengths and growth directions provided by this CVD technique is used to fabricate ordered, large-scale nanotube structures. The Figure shows an ultralong SWNT.

    19. Coating BaTiO3 Nanolayers on Spherical Ni Powders for Multilayer Ceramic Capacitors (pages 1655–1658)

      J.-Y. Lee, J.-H. Lee, S.-H. Hong, Y.K. Lee and J.-Y. Choi

      Version of Record online: 7 OCT 2003 | DOI: 10.1002/adma.200305418

      A nanometer-thick BaTiO3 coating layer has been prepared on spherical Ni. The BaTiO3 coating effectively retards the low-temperature sintering between Ni particles and improves the resistance against Ni oxidation. This technology provides a useful tool to fabricate highly integrated multilayer ceramic capacitors (MLCCs). The Figure shows the nanometer-thick BaTiO3 hollow spheres after core (Ni) removal.