Advanced Materials

Cover image for Advanced Materials

October, 2004

Volume 16, Issue 20

Pages 1775–1866

    1. Chromogenic Discrimination of Primary Aliphatic Amines in Water with Functionalized Mesoporous Silica (pages 1783–1786)

      M. Comes, M. D. Marcos, R. Martínez-Máñez, F. Sancenón, J. Soto, L. A. Villaescusa, P. Amorós and D. Beltrán

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400143

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      Tuning of the sensing abilities of certain chromogenic molecules is achieved by anchoring them to modified MCM-41-type solids. This approach allows chromogenic detection of primary aliphatic amines of a certain length in water. The Figure shows color changes of the functionalized solid (magenta–yellow) in the presence of n-heptylamine, n-octylamine, and n-nonylamine. Longer or shorter aliphatic chains induced no significant color variation.

    2. Light-Induced Transformation of Molecular Materials into Devices (pages 1786–1790)

      T. Naito, T. Inabe, H. Niimi and K. Asakura

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400308

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      Single crystals of a silver/organic charge-transfer complex are doped by illumination via optical fibers (see Figure). Continuous illumination with UV–visible light induces electron transfer between the organic π-acceptor and a silver ion in the organic charge-transfer complex in the solid state. Illumination of one half of a single crystal produces a p–n junction rectifier in a single step.

    3. Nanostructured and Transparent Polymer Membranes with Thermosensitivity for Wound Dressing and Cell Grafting (pages 1790–1794)

      L.-S. Wang, P.-Y. Chow, D. C.-W. Tan, W.-D. Zhang and Y.-Y. Yang

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400602

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      Transparent and nanostructured polymer membranes (see Figure of cells attached to membrane surface) have been fabricated successfully via the polymerization of bicontinuous microemulsions. The resultant membranes demonstrate temperature-dependent swelling behavior with increased water uptake at lower temperatures. These membranes could be used as wound dressings or as support for cell grafting.

    4. Nano-Anemones: Stimulus-Responsive Copolymer-Micelle Surfaces (pages 1794–1798)

      G. B. Webber, E. J. Wanless, S. P. Armes, Y. Tang, Y. Li and S. Biggs

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400086

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      Robust, stimulus-responsive thin films are prepared by self-assembly of diblock-copolymer micelles from aqueous solution. Atomic force microscopy and fluorescence spectroscopy show that the hydrophobic polymer cores of block copolymer micelles adsorbed at high pH become localized cationic polymer brushes reversibly at low pH without micellar desorption (see Figure).

    5. DNA-Templated Assembly of a Protein-Functionalized Nanogap Electrode (pages 1799–1803)

      A. Ongaro, F. Griffin, L. Nagle, D. Iacopino, R. Eritja and D. Fitzmaurice

      Version of Record online: 14 OCT 2004 | DOI: 10.1002/adma.200400244

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      The DNA-templated assembly of a protein-functionalized 10 nm gap electrode from suitably modified gold nanoparticles on a silicon wafer substrate is reported (see Figure). Additionally, the protein-functionalized electrode is recognized and bound selectively by a suitably modified 5 nm diameter gold nanoparticle localized in the 10 nm gap.

    6. A Helical π-Radical-Cation Column in the Double Helix of Mellitate Anions (pages 1803–1806)

      N. Kobayashi, T. Naito and T. Inabe

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400495

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      A tetrathiafulvalene (TTF) π-radical-cation salt with a unique helical-column structure (see Figure) was constructed using a supramolecular double-helix network of mellitate anions. The TTF radical tends to dimerize in a one- dimensional column, but a twisting distortion induces a kink defect. Utilizing the supramolecular network of a counterion is a promising method for the design of novel functional molecular materials.

    7. Stable New Sensitizer with Improved Light Harvesting for Nanocrystalline Dye-Sensitized Solar Cells (pages 1806–1811)

      P. Wang, S. M. Zakeeruddin, J. E. Moser, R. Humphry-Baker, P. Comte, V. Aranyos, A. Hagfeldt, M. K. Nazeeruddin and M. Grätzel

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400039

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      A new heteroleptic polypyridyl ruthenium complex (see Figure) with a high molar extinction coefficient has been synthesized. The complex is demonstrated to be a highly efficient, stable sensitizer for nanocrystalline dye-sensitized solar cells. For a newly developed dye, the achievement of 10.2 % power conversion efficiency is very encouraging.

    8. Porous Silicon Photonic Crystals as Encoded Microcarriers (pages 1811–1814)

      S. O. Meade, M. S. Yoon, K. H. Ahn and M. J. Sailor

      Version of Record online: 23 SEP 2004 | DOI: 10.1002/adma.200400713

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      A simple method used to construct microparticles of porous Si photonic crystals that display highly resolved and easily controlled optical diffraction peaks is described. The spectral diffraction peaks can act as digits in an encoding scheme, and the possibility of generating particle libraries with >106 distinct codes is demonstrated (see Figure).

    9. Two-Dimensional, Open-Pored, Mesoscopic Titania Layers Using Polymeric Nanoparticle Monolayers as a Template (pages 1814–1817)

      Y.-H. Cho, G. Cho and J.-S. Lee

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400249

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      Open-pored mesoscopic 2D titania layers (see Figure) were fabricated by using a nanoparticle layer as a template. Monodisperse polymer particles approximately 60 nm in diameter were spontaneously formed by dissolving polystyrene-b-poly(N-methyl-2-vinylpyridinium iodide) in toluene. These particles self-assembled at the air–water interface to form well-ordered monolayers, which were then used as templates in a sol–gel reaction to form porous 2D titania layers with a pore size of ∼ 55 nm.

    10. Direct Synthesis of Novel FeSBA-1 Cubic Mesoporous Catalyst and Its High Activity in the tert-Butylation of Phenol (pages 1817–1821)

      A. Vinu, T. Krithiga, V. Murugesan and M. Hartmann

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400229

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      A novel method used to incorporate iron into the three-dimensional mesoporous cubic SBA-1 materials in highly acidic media is presented. The amount of iron present is controlled by simply adjusting the molar hydrochloric acid to silicon ratio. Moreover, the novel catalyst shows significantly higher phenol conversion and 4-tert- butylphenol selectivity in the tertiary butylation of phenol (see Figure).

    11. Enhancing the Rate of Energy Release from NanoEnergetic Materials by Electrostatically Enhanced Assembly (pages 1821–1825)

      S. H. Kim and M. R. Zachariah

      Version of Record online: 23 SEP 2004 | DOI: 10.1002/adma.200306436

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      Electrostatically enhanced nanocomposite particle assembly as a viable method of enhancing the reactivity of energetic nanocomposites is reported. The kinetics of the burning process can be be tailored, and differential scanning calorimetry (DSC) results demonstrate that bipolar- assembly synthesized aluminum/iron oxide nanocomposite aerosol materials have burning rates an order of magnitude higher than those produced via random Brownian coagulation.

    12. Efficient Electron Injection from a Bilayer Cathode Consisting of Aluminum and Alcohol-/Water-Soluble Conjugated Polymers (pages 1826–1830)

      H. Wu, F. Huang, Y. Mo, W. Yang, D. Wang, J. Peng and Y. Cao

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400067

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      A bilayer cathode consisting of aminoalkyl-substituted polyfluorene and Al layers (see Figure) effectively injects electrons into an electroluminescent polymer emitting layer. The alcohol- and water-soluble polyfluorene, and its quaternized salt, can be used to fabricate polymer light-emitting diodes with device performance comparable to, or exceeding, devices using Ba/Al cathodes.

    13. Facile Creation of a Bionic Super-Hydrophobic Block Copolymer Surface (pages 1830–1833)

      Q. Xie, G. Fan, N. Zhao, X. Guo, J. Xu, J. Dong, L. Zhang and Y. Zhang

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400074

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      A super-hydrophobic surface (see Figure), possessing a microscale and nanoscale hierarchical structure similar to the surface structure of the lotus leaf, was prepared in one step from a micellar solution of polypropylene-block-poly(methyl methacrylate).

    14. Growth of Single-Crystal Indium Nitride Nanotubes and Nanowires by a Controlled-Carbonitridation Reaction Route (pages 1833–1838)

      L.-W. Yin, Y. Bando, D. Golberg and M.-S. Li

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200306684

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      Single-crystal InN nanotubes and nanowires with a strong photoluminescence emission at 640 nm have been synthesized via a controlled-carbonitridation thermal chemical route. Formation of the nanotubes and nanowires proceeds by a kinetically limited growth process via a vapor–solid (VS) mechanism, and does not require a template to form single-layer nanostructures.

    15. Fabrication of Protein/Silica Core–Shell Nanoparticles by Microemulsion-Based Molecular Wrapping (pages 1838–1841)

      D. Ma, M. Li, A. J. Patil and S. Mann

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400351

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      A novel process for wrapping individual myoglobin molecules with an ultrathin shell of silica is reported. Confinement of single protein molecules in microemulsion water droplets followed by the controlled hydrolysis and condensation of tetramethoxysilane at the oil/water interface produces discrete protein/ silica nanoparticles (see Figure) without loss of myoglobin structure and function.

    16. A New Method for the Preparation of Metal Nanowires by the Nebulized Spray Pyrolysis of Precursors (pages 1842–1845)

      S. R. C. Vivekchand, G. Gundiah, A. Govindaraj and C. N. R. Rao

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400430

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      A new method based on nebulized spray pyrolysis is applied to the preparation of metal (zinc, cadmium, cobalt, and lead) nanowires. The resulting nanowires are single- crystalline. The oxidation of metal nanowires yields one-dimensional oxidic nanostructures. In the case of zinc metal, tubular ZnO is obtained.

    17. Core–Shell Synthesis of a Novel, Spherical, Mesoporous Silica/Platinum Nanocomposite: Pt/PVP@MCM-41 (pages 1845–1849)

      K.-J. Lin, L.-J. Chen, M. R. Prasad and C.-Y. Cheng

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400349

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      A spherical, disordered, wormhole-like nanocomposite, consisting of 115 nm diameter MCM-41 particles containing 3 nm diameter Pt nanoparticles (see Figure), is described. A surfactant that stabilizes and prevents aggregation of the Pt nanoparticles during synthesis is removed by calcination, resulting in a high Pt catalytic surface area. Multiple cycles of cinnamic acid hydrogenation at room temperature demonstrate the potential of this reusable catalytic nanocomposite.

    18. Diamond Nanorods from Carbon Nanotubes (pages 1849–1853)

      L. T. Sun, J. L. Gong, D. Z. Zhu, Z. Y. Zhu and S. X. He

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400429

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      The synthesis of single-crystalline diamond nanorods (with diameters of 4–8 nm and with lengths up to 200 nm) via the hydrogen plasma post-treatment of multiwalled carbon nanotubes is described. The diamond nanorods (see Figure) are identified as having a core–sheath structure with the inner core being diamond crystal and the outer shell being composed of amorphous carbon. A growth mechanism for diamond nanorods is proposed.

    19. Preparation of the Novel Nanocomposite Co(OH)2/ Ultra-Stable Y Zeolite and Its Application as a Supercapacitor with High Energy Density (pages 1853–1857)

      L. Cao, F. Xu, Y.-Y. Liang and H.-L. Li

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400183

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      A Co(OH)2/zeolite nanocomposite with an extraordinarily high specific capacitance is described. Nanometer-sized Co(OH)2 whiskers on the zeolite surface permit high electrochemical accessibility and a fast diffusion rate of electrolyte through the material, resulting in a specific capacitance approaching the theoretical limit. Increasing the Co(OH)2 loading increases whisker growth (see Figure), until bulk Co(OH)2 begins to nucleate and grow in solution (arrows).

    20. Tubes with Controllable Internal Nanotopography (pages 1857–1860)

      N. Gadegaard, M. J. Dalby, M. O. Riehle, A. S. G. Curtis and S. Affrossman

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400408

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      Preparation of tubes with an internal nanotopography based on polymer de-mixing is presented. A solution of two polymers is quickly blown through a tube, forming a nanotopographic surface. The shape and feature size can be partially controlled. The Figure shows a 3D representation of the topography inside a glass tube measured using atomic force microscopy, clearly showing the curvature of the tube (image size: 15 μm × 15 μm).

    21. Silicone Nanocapsules from Catanionic Vesicle Templates (pages 1861–1863)

      M. Kepczynski, F. Ganachaud and P. Hémery

      Version of Record online: 8 NOV 2004 | DOI: 10.1002/adma.200400537

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      Preparation of water-filled silicone nanocapsules of controlled size is reported. Catanionic vesicles are used as templates for tetramethylcyclotetrasiloxane (D4H) crosslinking reactions inside their bilayers. Various characterization techniques confirmed the synthesis of nonporous, impermeable, highly crosslinked, hollow spheres about 100 nm in diameter.