Advanced Materials

Cover image for Advanced Materials

February, 2004

Volume 16, Issue 3

Pages 195–278

    1. Contents: Adv. Mater. 3/2004 (pages 195–201)

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200490006

    2. Inkjet Printing of Polymers: State of the Art and Future Developments (pages 203–213)

      B.-J. de Gans, P. C. Duineveld and U. S. Schubert

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200300385

      In the field of defined polymer deposition inkjet printing is considered to be a key technology. Besides an introduction to inkjet printing technology, a short overview of the available instrumentation as well as several examples of polymer inkjet printing are provided. Special emphasis is directed towards polymer structure, molar mass, and solvents. The Figure shows an array of inkjet-printed droplets.

    3. Direct Writing of Patterned Ceramics Using Electron-Beam Lithography and Metallopolymer Resists (pages 215–219)

      S. B. Clendenning, S. Aouba, M. S. Rayat, D. Grozea, J. B. Sorge, P. M. Brodersen, R. N. S. Sodhi, Z.-H. Lu, C. M. Yip, M. R. Freeman, H. E. Ruda and I. Manners

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200305740

      Patterned arrays of ceramics have been fabricated using electron-beam lithography (EBL) and a metallopolymer resist. Highly ordered arrays of dots, bars (see scanning electron microscopy and time-of-flight secondary ion mass spectrometry images in the Figure), and curved lines rich in Fe and Co are direct-written on films of a highly metallized cobalt-clusterized polyferrocenylsilane. Subsequent pyrolysis leads to ferromagnetic ceramics.

    4. Phototactic Mass Transport in Polymer Films for Micropatterning and Alignment of Functional Materials (pages 220–223)

      T. Ubukata, M. Hara, K. Ichimura and T. Seki

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200305535

      A new micropatterning technique based on photoinduced mass transport in a polymer film is presented. The Figure shows a rod-like dye crystallized aligned along a surface relief grating (SRG) on an azobenzene polymer film produced by photoirradiation through a photomask. The uniaxial alignment is achieved by one-dimensional diffusion—restricted by the grating geometry—of the dye molecule.

    5. Immobilization of Protein Molecules by Size-Selected Metal Clusters on Surfaces (pages 223–226)

      C. Leung, C. Xirouchaki, N. Berovic and R. E. Palmer

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200305756

      Protein immobilization by nanocluster films is a new route to stabilize individual protein molecules and complexes for single-molecule measurements such as liquid-phase atomic force microscopy (AFM) imaging (see Figure). The sub-monolayer films of size-selected Au clusters present protein binding sites of arbitrary density.

    6. Highly Oriented and Ordered Arrays from Block Copolymers via Solvent Evaporation (pages 226–231)

      S. H. Kim, M. J. Misner, T. Xu, M. Kimura and T. P. Russell

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200304906

      A simple process of solvent evaporation is shown to produce highly ordered arrays of cylindrical microdomains in block copolymers with long-range lateral order (see Figure). Solvent evaporation in thin films is unidirectional, producing a self-assembly directed normal to the film surface, akin to a zone refinement. Further control over the size and separation distance of the domains can be achieved with cosolvents.

    7. Crystalline Colloidal Arrays Composed of Poly(3,4-ethylenedioxythiophene)-Coated Polystyrene Particles with a Stop Band in the Visible Regime (pages 231–234)

      M. G. Han and S. H. Foulger

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200305642

      Monodisperse polystyrene particles with a diameter of ca. 100 nm have been coated with 8 nm shells of poly(3,4-ethylenedioxythiophene) (PEDOT) and self-assembled into crystalline colloidal arrays (see Figure) with an observed stop band in the visible regime. These materials could be used in developing photonic crystals with frequency- and dopant-dependent optical properties .

    8. Aligned Gold Nanorods in Silica Made by Ion Irradiation of Core–Shell Colloidal Particles (pages 235–237)

      S. Roorda, T. van Dillen, A. Polman, C. Graf, A. van Blaaderen and B. J. Kooi

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200305742

      Colloidal particles with a 14 nm diameter Au core surrounded by a 72 nm thick silica shell have been irradiated with 30 MeV heavy ions. The shell deforms into an oblate ellipsoid, while the core becomes rod-shaped (aspect ratio up to 9) with the major axis along the beam. Optical extinction measurements show evidence for split plasmon bands, characteristic for anisotropic metal nanoparticles.

    9. Porous Tin Oxides Prepared Using an Anodic Oxidation Process (pages 237–240)

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

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200305660

      Open, porous structures of tin oxides, fabricated by an anodic oxidation process, are characterized by irregular channels with diameters of several tens of nanometers, as shown in the Figure. The as-prepared amorphous tin oxides can be transformed by annealing to a crystalline stannic structure with very few micro-structural changes. The materials may find applications in batteries and chemical sensors.

    10. Thermally Assisted Sub-10 fs Electron Transfer in Dye-Sensitized Nanocrystalline TiO2 Solar Cells (pages 240–244)

      W. Stier, W. R. Duncan and O. V. Prezhdo

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200306027

      The sub-10 fs photoinduced electron transfer from alizarin molecules to titania nanoparticles is simulated (see Figure; white: H; black: C; red: O; gray: Ti). The system provides a paradigm of the nanoscale coupling of organic and inorganic species. Remarkably, conduction is possible with photoexcitation below the conduction band and occurs by thermal activation.

    11. Rapid Fabrication of Binary Colloidal Crystals by Stepwise Spin-Coating (pages 244–247)

      D. Wang and H. Möhwald

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200305565

      Binary colloidal crystals (see Figure) of large (L) and small (S) silica colloidal spheres with large diameter ratios have been rapidly constructed by stepwise spin-coating. The dominant structure of the resultant crystals is LS2, with which the LS3 structure usually coexists. The diameter ratio and the speed of spin-coating are used to control the structures, with higher spin speeds favoring the formation of LS3 structures.

    12. Preparation of Conductive Nanotube–Polymer Composites Using Latex Technology (pages 248–251)

      O. Regev, P. N. B. ElKati, J. Loos and C. E. Koning

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200305728

      Composites consisting of individual, or bundles of single-walled, exfoliated nanotubes in a highly viscous polymer matrix (see Figure) are described. The nanotubes and polymer are made compatible using surfactant molecules, hence avoiding the need for direct attraction between the nanotubes and the matrix. The resulting nanotube–polymer composites have a conductivity percolation threshold of 0.28 wt.-% nanotubes.

    13. Characterizing Joule Heating in Polymer Light-Emitting Diodes Using a Scanning Thermal Microscope (pages 252–256)

      F. A. Boroumand, A. Hammiche, G. Hill and D. G. Lidzey

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200306128

      Scanning thermal microscopy (SThM) has been used to study Joule heating in conjugated polymer light-emitting diodes (LEDs; see Figure). The operational temperature of the LED is found to be a strong function of device area: smaller LEDs exchange heat more efficiently with their surrounding environment. The results suggest that at high current density, Joule heating may be linked to device failure.

    14. Novel Nanostructured Electrodes for Solid Oxide Fuel Cells Fabricated by Combustion Chemical Vapor Deposition (CVD) (pages 256–260)

      Y. Liu, S. Zha and M. Liu

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200305767

      Highly porous and nano-structured electrodes for low-temperature solid oxide fuel cells have been fabricated using a combustion chemical vapor deposition process. The composite electrodes consist of small grains, about 50 nm as shown in the Figure, have extremely high surface area, low interfacial polarization resistances, and high performance at low operating temperatures.

    15. Nanocarving of Bulk Titania Crystals into Oriented Arrays of Single-Crystal Nanofibers via Reaction with Hydrogen-Bearing Gas (pages 260–264)

      S. Yoo, S. A. Akbar and K. H. Sandhage

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200305781

      Oriented arrays of titania nanofibers have been fabricated by a simple and easily scalable method. Exposure to a 5 % H2/95 % N2 gas mixture at 700 °C transforms dense, polycrystalline rutile (TiO2) into arrays of single-crystal nanofibers (15–50 nm diameter; see Figure, scale bar: 1 μm). The arrays could be used in of environmental, biomedical, transportation, chemical processing, and sensing applications.

    16. Multiple-Walled Nanotubes Made of Metals (pages 264–268)

      Y. Sun and Y. Xia

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200305780

      Metal nanotubes with multiple walls (see Figure) have been synthesized in bulk quantities using a combination of galvanic replacement reaction (between Ag nanowires and salt precursors) and an electroless plating process of silver. These nanotubes with controllable structure, composition, and morphology are expected to find uses ranging from catalysis to gas storage, optoelectronics, electronics, and optical sensing.

    17. Receptor-Mediated Self-Assembly of Multi-Component Magnetic Nanowires (pages 268–271)

      A. K. Salem, J. Chao, K. W. Leong and P. C. Searson

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200305700

      The directed orientation of ferromagnetic nanowires tethered to spatially controlled regions of a surface is reported. The Figure is a light microscope image of 9 μm-long, two-segment Au/Ni nanowires with a biotinylated Au segment tethered to patterned avidin tracks. The aspect ratio of the nickel segments is ∼ 50, so the magnetic easy axis is parallel to the wire axis. The nanowires have rotated to be parallel to an applied magnetic field.

    18. Highly Efficient Biocatalysts via Covalent Immobilization of Candida rugosa Lipase on Ethylene Glycol-Modified Gold–Silica Nanocomposites (pages 271–274)

      U. Drechsler, N. O. Fischer, B. L. Frankamp and V. M. Rotello

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200306022

      The polymer-mediated self-assembly of silica and gold nanoparticles (see inset in Figure and cover) leads to extended aggregates. After calcination and subsequent surface modification, these aggregates serve as supports for the covalent immobilization of lipase (see Scheme). The obtained biocatalysts exhibit high efficiencies and long-term stability.

    19. A Snowman-like Array of Colloidal Dimers for Antireflecting Surfaces (pages 274–277)

      H. Y. Koo, D. K. Yi, S. J. Yoo and D.-Y. Kim

      Version of Record online: 11 FEB 2004 | DOI: 10.1002/adma.200305617

      Fabrication of motheye-like colloidal surface patterns as an antireflection coating is presented. Using layer-by-layer assembly and a novel colloid-on-colloid stamping strategy, snowman-like patterns consisting of different-sized colloids were fabricated (see Figure). The pattern spacing and height can be easily tailored by varying the salt concentration and the number of colloidal layers attached, respectively.