Advanced Materials

Cover image for Vol. 15 Issue 9

May, 2003

Volume 15, Issue 9

Pages 663–750

    1. Contents: Adv. Mater. 9/2003 (pages 663–667)

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200390137

    2. Reader's Information: DOI (page 668)

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200390138

    3. Ionic Self-Assembly: Facile Synthesis of Supramolecular Materials (pages 673–683)

      C.F.J. Faul and M. Antonietti

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200300379

      Ionic self-assembly (ISA), the coupling of chemically very different building blocks by electrostatic interactions, has become a powerful tool for creating new nanostructures and chemical objects, as highlighted here. For example, with an appropriate surfactant counterion, glutathione disulfide forms extended and well-defined superhelices, the composition of which is schematically illustrated in the Figure.

    4. Photonic Crystal Composites with Reversible High-Frequency Stop Band Shifts (pages 685–689)

      S.H. Foulger, P. Jiang, A. Lattam, D.W. Smith Jr., J. Ballato, D.E. Dausch, S. Grego and B.R. Stoner

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304566

      The fabrication of photonic crystal composites composed of encapsulated electrostatically stabilized colloidal arrays with tailorable thermomechanical properties is introduced. Composites with sub-ambient Tg exhibited reversible mechanochromic characteristics and a 172 nm stop-band tuning range, and could be modulated up to frequencies of 200 Hz. The Figure shows reflective characteristics of the composites at different strain levels (see also inside front cover).

    5. Virus-Based Alignment of Inorganic, Organic, and Biological Nanosized Materials (pages 689–692)

      S.-W. Lee, S.K. Lee and A.M. Belcher

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304818

      A self-ordering system based on anti-streptavidin viruses is presented. A variety of materials, including inorganic nanoparticles, small organic molecules, and large biomolecules, can be organized at the nanometer length scale using this method. Molecular recognition is used to bind nanosize materials (e.g., gold nanoparticles) to the virus (see cover) and the resulting complex spontaneously evolves into a self-supporting hybrid film (see Figure).

    6. Bioactive Coatings Based on a Polyelectrolyte Multilayer Architecture Functionalized by Embedded Proteins (pages 692–695)

      N. Jessel, F. Atalar, P. Lavalle, J. Mutterer, G. Decher, P. Schaaf, J.-C. Voegel and J. Ogier

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304634

      Does a signal protein imbedded in a polyelectrolyte layer keep its activity? The study reported here demonstrates that cells can indeed interact with proteins incorporated in poly(L-lysine/glutamic acid) multilayer films. In contrast, poly(D-lysine) acts as a barrier to cell communication. For the case of monocytic cells the mechanism of contact with the active protein is elucidated. It is believed that such functionalized coatings could be useful tools for the modification of biomaterial surfaces with applications in, e.g., implants or tissue engineering.

    7. Triangular Nanoplates of Silver: Synthesis, Characterization, and Use as Sacrificial Templates For Generating Triangular Nanorings of Gold (pages 695–699)

      Y. Sun and Y. Xia

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304652

      Triangular nanoplates of silver are prepared by irradiating aqueous dispersions of spherical silver colloids with visible light in the presence of both poly(vinyl pyrrolidone) and sodium citrate. These silver nanoplates serve as sacrificial templates to generate triangular rings of gold (see transmission electron microscopy images in Figure) through a galvanic displacement reaction between silver and aqueous HAuCl4 solutions.

    8. Effect of Molecular Orientation of Epitaxially Grown Platinum(II) Octaethyl Porphyrin Films on the Performance of Field-Effect Transistors (pages 699–702)

      Y.-Y. Noh, J.-J. Kim, Y. Yoshida and K. Yase

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304005

      The molecular alignment of platinum(II) octaethyl porphyrin (PtOEP) crystals evaporated on KBr (see atomic force microscopy image, Figure) can be readily changed from perpendicular to parallel by changing the substrate temperature. The field-effect mobility of transisitors prepared using epitaxially grown PtOEP films aligned perpendicularly to a substrate is 100 times higher than that of those of parallel alignment.

    9. Hierarchical Pattern Replication by Polymer Demixing (pages 703–706)

      M. Sprenger, S. Walheim, C. Schäfle and U. Steiner

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304463

      Structures with a lateral size of ≈ 100 nm have been created using a new replication method based on the demixing of a ternary polymer mixture during spin-coating. The technique, which relies on the interfacial wetting of one of the polymer components at the interface of the other two, produces structures (see Figure) that are significantly smaller than the lateral dimensions of the substrate prepattern.

    10. Palladium Nanotubes with Tailored Wall Morphologies (pages 706–709)

      M. Steinhart, Z. Jia, A.K. Schaper, R.B. Wehrspohn, U. Gösele and J.H. Wendorff

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304502

      Wetting of porous templates by multi-component mixtures followed by demixing and controlled morphology ripening is a universal method to prepare nanotubes with tailored wall morphologies (see Figure). This is demonstrated here exemplarily by means of palladium nanotubes with a specific nano-roughness and porosity.

    11. Selected Polymorphs of CaCO3 Through Epitaxy with Inorganic Substrates Aligned with an Electric Field (pages 709–712)

      I.W. Kim, R.E. Robertson and R. Zand

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304413

      The epitaxial requirement for the selection of metastable arogonite among the polymorphs of calcium carbonate has been studied. Under calcite-favorable conditions, the critical epitaxial strain with aragonite-type inorganic substrates was found to be in the range 5–7 %. The Figure shows aragonite “fuzz” grown on SrCO3 crystals that were aligned and fractured perpendicular to the alignment axis.

    12. Face-Centered-Cubic “Supracrystals” of Cobalt Nanocrystals (pages 712–716)

      I. Lisiecki, P.-A. Albouy and M.-P. Pileni

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304417

      Magnetic “supra” crystals have been built by slow evaporation of a solution of 7.2 nm cobalt nanoparticles in hexane. Scanning electron microscopy shows isolated pavements which height is of the order of 5 μm (see Figure). Investigation made by small-angle X-ray diffraction clearly indicates a face-centered cubic structure.

    13. A Strong Correlation Between the Hole Mobility and Silicon Chain Length in Oligosilane Self-Organized Thin Films (pages 716–720)

      H. Okumoto, T. Yatabe, A. Richter, J. Peng, M. Shimomura, A. Kaito and N. Minami

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304809

      A unique and systematic correlation has been found between the hole mobility of oligosilane polycrystalline thin films and the length of the constituent molecules: the mobility increases with the silicon chain length in a zigzag fashion (odd–even effect—see Figure). Such strong correlation is shown to be brought about by the self-organized structure of the films, wherein molecules form highly ordered multilayers extending to a macroscopic scale.

    14. Novel Route to Cubic Boron Nitride Dendritic Nanostructures under Electron Beam Irradiation (pages 720–723)

      L.-W. Yin, M.-S. Li, Y.-X. Liu, B. Xu, J.-L. Sui and Y.-X. Qi

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304674

      The growth of c-BN dendritic nanostructures (see Figure) has been investigated in situ using a combination of characterization techniques. It is concluded that the electron beam irradiation induced nucleation and growth of the nanostructures in vacuum is closely related to the nanoarches at the edge of the h-BN starting material. A solid-sate mechanism different from the traditional one for BN nanostructure growth from the gas phase is proposed.

    15. Photorefractive Performance Enhancement in Polymer Dispersions of Nanosized Crystalline Domains (pages 723–726)

      R. Termine, I. Aiello, D. Dattilo, M. Ghedini and A. Golemme

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304768

      Photorefractive polymeric nanosized dispersions of crystalline materials with high dynamic range have been developed using controlled phase-separation techniques. Orientational birefringence is induced by internal electric fields via the dielectric anisotropy of crystalline domains, rather than through the usual reorientation of molecular dipoles. This more efficient mechanism can increase photorefractive performance by two orders of magnitude and can in principle be applied to optimize other materials for a variety of applications, including medical imaging and image processing.

    16. Synthesis of Novel Nickel Sulfide Submicrometer Hollow Spheres (pages 726–729)

      Y. Hu, J. Chen, W. Chen, X. Lin and X. Li

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304687

      Nickel sulfide uniform hollow spheres (see scanning electron microscopy image, Figure) have been successfully synthesized by γ-irradiation of a PMMA–CS2–ethanol aqueous solution that contains NiSO4·6H2O at room temperature. Calculation shows that the diameter of the NiS hollow spheres is 500 nm and the thickness of shell is ∼ 20 nm. A possible growth mechanism is also presented.

    17. Highly CO2-Permeable and Selective Polymer Nanocomposite Membranes (pages 729–733)

      N.P. Patel, A.C. Miller and R.J. Spontak

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304712

      As technologies turn to more efficient routes to remove CO2 from mixed gas streams for H2 or air purification, new cost-effective multifunctional materials are needed for the separation processes. Here, hybrid poly(ethylene glycol)/fumed silica nanocomposite membranes exhibiting high CO2/H2 selectivity (> 11) and CO2 permeability (∼ 83 Barrer), as well as robust mechanical properties and optical clarity, are reported (see Figure).

    18. Shear and Young's Moduli of MoS2 Nanotube Ropes (pages 733–736)

      A. Kis, D. Mihailovic, M. Remskar, A. Mrzel, A. Jesih, I. Piwonski, A.J. Kulik, W. Benoît and L. Forró

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304549

      The interaction between individual nanotubes in MoS2 bundles is investigated here using an atomic force microscope (AFM). Upon elastically deforming the ropes with the AFM, the value of the bending modulus of the MoS2 tube ensemble could be evaluated. This is turn could be used to obtain a lower estimate of the shear and Young's moduli of the nanotubes. The results indicate that the MoS2 ropes are highly anisotropic and that the interaction between the individual tubes comprising the rope is very weak.

    19. Reversible Formation and Decomposition of LiF Clusters Using Transition Metal Fluorides as Precursors and Their Application in Rechargeable Li Batteries (pages 736–739)

      H. Li, G. Richter and J. Maier

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304574

      A LiF/M nanocomposite in which LiF is dispersed with a transition metal (TM) on an atomic or nanometer scale can be obtained by a complete electrochemical insertion of Li into TM fluoride. Thus Li–F bonds can be broken and reformed at room temperature, and Li can be reversibly stored in TM fluorides through heterogeneous solid-state electrochemical reactions (see Figure).

    20. Synthesis of Crystalline Mesoporous CdS Semiconductor Nanoarrays Through a Mesoporous SBA-15 Silica Template Technique (pages 739–742)

      F. Gao, Q. Lu and D. Zhao

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304758

      A novel crystalline mesoporous CdS semiconductor (see Figure) has been synthesized with the aid of a mesoporous silica template through a simple single precursor decomposition route at low temperature. The precursor used—cadmium thioglycolate [Cd10S16C32H80 N4O28]—is not only the Cd but also the S source. The resultant CdS material is an inverse replica of the silica template and retains its mesostructured order.

    21. Size-Controlled Synthesis and Catalytic Performance of Pt Nanoparticles in Micro- and Mesoporous Silica Prepared Using Supercritical Solvents (pages 742–745)

      H. Wakayama, N. Setoyama and Y. Fukushima

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304408

      A novel impregnation process using a supercritical fluid (SCF) solvent to generate size-controlled Pt nanoparticles in micro- and mesoporous silica hosts with a uniform pore size (see Figure) is presented. The size of the Pt nanoparticles decreases with the pore size of silica hosts, and the SCFs are shown to be excellent solvents for the introduction of nanoparticles into fine spaces on a nanometer scale.

    22. A Multi-Addressable Photochromic 1,2-Dithienylcyclopentene-Phenoxynaphthacenequinone Hybrid (pages 745–748)

      A.J. Myles, T.J. Wigglesworth and N.R. Branda

      Version of Record online: 25 APR 2003 | DOI: 10.1002/adma.200304917

      Four unique states of the photochromic hybrid shown in the Figure can be independently addressed using light energy as the only input. This system benefits from the photochromic properties of the 1,2-dithienylcyclopentene and phenoxynaphthacenequinone scaffolds and represents the first quaternary photo-switch in which all states are thermally stable.