Advanced Materials

Cover image for Vol. 13 Issue 10

May, 2001

Volume 13, Issue 10

Pages 703–768

    1. Organic–Inorganic Nanocomposites: Unique Resists for Nanolithography (pages 703–714)

      K. E. Gonsalves, L. Merhari, H. Wu and Y. Hu

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<703::AID-ADMA703>3.0.CO;2-A

      An optimum combination of high contrast, necessary for sub-100 nm resolution, and high sensitivity for high throughput can be achieved by carefully engineering organic–inorganic nanocomposites. This review outlines emerging approaches towards the achievement of these goals. One of the approaches is the inclusion of fullerene C60 in a commercial resist ZEP520 for sub-100 nm features (see Figure).

    2. Nanotube Formation from Renewable Resources via Coiled Nanofibers (pages 715–718)

      G. John, M. Masuda, Y. Okada, K. Yase and T. Shimizu

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<715::AID-ADMA715>3.0.CO;2-Z

      Self-assembly of glycolipids into open-ended organic nanotubes (see Figure) is reported here. Depending on the solvent system used and the degree of saturation of the glycolipid, either gels or nanofibers of various morphologies form. Upon standing, the unsaturated glycolipid–based nanofibers transform into nanotubes with inner diameter 10–15 nm and length 10–100 μm.

    3. Free-Standing Thin Films Containing Hexagonally Organized Silver Nanocrystals in a Polymer Matrix (pages 718–721)

      M. H. Lim and D. G. Ast

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<718::AID-ADMA718>3.0.CO;2-N

      The successful preparation of novel thin nanocomposite films containing continuous periodic arrays of self-assembled silver nanocrystals in a polystyrene (PS) matrix is reported in this communication. The Figure shows a photo of a thin nanocomposite Ag–PS film supported by a wire loop. The simple and rapid synthetic procedure described here should be applicable to a variety of metal or semiconductor–polymer nanocomposite systems.

    4. Epitaxial Growth of High Dielectric Contrast Three-Dimensional Photonic Crystals (pages 721–724)

      P. V. Braun, R. W. Zehner, C. A. White, M. K. Weldon, C. Kloc, S. S. Patel and P. Wiltzius

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<721::AID-ADMA721>3.0.CO;2-A

      The facile creation of oriented single crystal colloidal assemblies directly on a silicon substrate and conversion to a high refractive index contrast photonic crystal is reported here. The route unveiled has great potential for applications in optoelectronics. The Figure displays the sharp boundary between colloidal crystal growth on patterned substrates and random colloidal assembly formation on unpatterned substrates.

    5. Alteration of Classical Microdomain Patterns of Block Copolymers by Degenerate Epitaxy (pages 724–728)

      C. Park, C. De Rosa, L. J. Fetters, B. Lotz and E. L. Thomas

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<724::AID-ADMA724>3.0.CO;2-Z

      Degenerate epitaxial crystallization of a semicrystalline block terpolymer is utilized to alter the polymer's normal microdomain structure. It is demonstrated that the strong interaction created by crystallographic matching of unit cells between the crystalline polyethylene (PE) block and the anthracene substrate forces the amorphous polystyrene (PS) cylindrical microdomains into a new nanoscale structure (see Figure).

    6. Hierarchically Ordered Ceramics Through Surfactant-Templated Sol-Gel Mineralization of Biological Cellular Structures (pages 728–732)

      Y. Shin, J. Liu, J. H. Chang, Z. Nie and G. J. Exarhos

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<728::AID-ADMA728>3.0.CO;2-J

      Wood tissues with ordered cellular structurecan be mineralized using the simple surfactant-templated sol-gel process presented here. Hierarchical porous ceramic materials that are a faithful reproduction of the biological tissue and that also contain organized nanoporous channels are obtained. The Figure shows a mineralized poplar sample after calcination (see also inside front cover).

    7. Polyferrocenylsilane and Magnetic Ceramic Microspheres (pages 732–736)

      K. Kulbaba, R. Resendes, A. Cheng, A. Bartole, A. Safa-Sefat, N. Coombs, H. D. H. Stöver, J. E. Greedan, G. A. Ozin and I. Manners

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<732::AID-ADMA732>3.0.CO;2-2

      Polyferrocenylsilane microspheres are readily formed under mild reaction conditions. Chemical oxidation leads to positively charged particles that undergo electrostatic self-assembly with smaller negatively charged silica microspheres, which leads to composite superstructures (see Figure), whereas pyrolysis leads to spherical magnetic ceramics that self-organize into two-dimensional arrays in a magnetic field.

    8. Electron-Beam Induced Formation of Highly Ordered Palladium and Platinum Nanoparticle Arrays on the S Layer of Bacillus sphaericusNCTC 9602 (pages 736–740)

      R. Wahl, M. Mertig, J. Raff, S. Selenska-Pobell and W. Pompe

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<736::AID-ADMA736>3.0.CO;2-N

      Regular arrays of metallic nanoparticles are formed by these authors using a novel technique involving electron-beam induced cluster formation in the transmission electron microscope (TEM). Nucleation is initiated in the cavities between crystalline bacterial surface layers deposited on a solid support, as schematically illustrated in the Figure.

    9. Hollow Titania Spheres from Layered Precursor Deposition on Sacrificial Colloidal Core Particles (pages 740–744)

      F. Caruso, X. Shi, R. A. Caruso and A. Susha

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<740::AID-ADMA740>3.0.CO;2-6

      The preparation of monodisperse hollow titania spheres with defined diameter, wall thickness, and crystal phase by the layer-by-layer templating of colloid particles and subsequent calcination (see Figure) is reported. A major advantage associated with this type of colloid templating is that it can be conducted from any aqueous solution. Nanometer-level control over the sphere wall thickness is achieved by varying the number of layers deposited on the particles.

    10. The Sense of Chromophore Orientation in Films Made by Alternating Polyelectrolyte Deposition (pages 744–746)

      W. N. Herman and M. J. Roberts

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<744::AID-ADMA744>3.0.CO;2-R

      The ability to pattern a substrate with hydrophobic and hydrophilic regions to control the sense of chromophore orientation in each region is unveiled in this work. It is shown that the hydrophobicity of the substrate determines the sense of the chromophore in multilayer second-order nonlinear optical polymer films (see Figure).

    11. Pure-Silica Zeolite Low-k Dielectric Thin Films (pages 746–749)

      Z. Wang, H. Wang, A. Mitra, L. Huang and Y. Yan

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<746::AID-ADMA746>3.0.CO;2-J

      Dielectric materials with a very low dielectric constant, k, will be required to overcome problems such as cross-talk and propagation delay in future generations of microprocessors, whose features are becoming increasingly smaller. Here pure-silica zeolite is examined as an alternative low-k material. Thin films prepared by in-situ crystallization (see Figure) and a spin-on process are compared.

    12. Room-Temperature Imprint Lithography (pages 749–752)

      D.-Y. Khang, H. Yoon and H. H. Lee

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<749::AID-ADMA749>3.0.CO;2-7

      Room-temperature imprint lithography showing unique features that are impossible to achieve with conventional high-temperature processes is unveiled here. Large-area nanopatterning, enabled by step-and-repeat and multiple imprinting (see Figure), leads to more versatile and practical nanoscale patterning.

    13. Shape-Persistent Polyphenylene Dendrimers—Restricted Molecular Dynamics from Advanced Solid-State Nuclear Magnetic Resonance Techniques (pages 752–756)

      M. Wind, U.-M. Wiesler, K. Saalwächter, K. Müllen and H. W. Spiess

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<752::AID-ADMA752>3.0.CO;2-V

      The molecular dynamics of polyphenylene dendrimers(e.g., the second generation dendrimer shown in the Figure) is investigated here using advanced solid-state NMR techniques. It is found that well-localized, restricted reorientation of single terminal phenyl substituents occurs around fixed axes only, clearly demonstrating the shape persistence of these dendrimers. The synthetic approach to these polyaromatic dendrimers is also described.

    14. Three-Dimensional Nano-objects Evolving from a Two-Dimensional Layer Technology (pages 756–759)

      O. G. Schmidt, N. Schmarje, C. Deneke, C. Müller and N.-Y. Jin-Phillipp

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<756::AID-ADMA756>3.0.CO;2-F

      A new concept for the fabrication of free-standing nano-objects is revealed. The technology involves controlled release and manipulation of thin solid films on substrate surfaces to yield novel nano-objects such as self-erecting, vertical, and ultra-thin membranes (see Figure), straight or twisted multi-material and multi-walled nanotubes (see cover), and advanced nanopipeline systems.

    15. Random Lasing in π-Conjugated Films and Infiltrated Opals (pages 760–764)

      R. C. Polson, A. Chipouline and Z. V. Vardeny

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<760::AID-ADMA760>3.0.CO;2-Z

      Random lasing is a generic phenomenon that occurs in disordered gain media at an excitation intensity regime higher than that giving rise to amplified spontaneous emission, as explained by these authors. The Figure shows a laser emission in several colors and the article unravels some of the main properties of random lasers in π-conjugated polymers and laser dyes.

    16. The Generation of Nanoparticles in Miniemulsions (pages 765–768)

      K. Landfester

      Version of Record online: 17 MAY 2001 | DOI: 10.1002/1521-4095(200105)13:10<765::AID-ADMA765>3.0.CO;2-F

      A versatile method for the generation of nanoparticulate metals, ceramics, and polymers based on synthesis in miniemulsions—highly stable small droplets in a continuous phase—is presented here. It is revealed that in addition to nanoparticles, encapsulated materials, polymer capsules (see Figure), and hollow particles can also be obtained by careful selection of the starting materials.