Advanced Materials

Cover image for Vol. 13 Issue 22

November, 2001

Volume 13, Issue 22

Pages 1655–1730

    1. Contents (pages 1655–1659)

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1655::AID-ADMA1655>3.0.CO;2-Z

    2. Formation of Nanowires along Ion Trajectories in Si Backbone Polymers (pages 1663–1665)

      S. Seki, K. Maeda, S. Tagawa, H. Kudoh, M. Sugimoto, Y. Morita and H. Shibata

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1663::AID-ADMA1663>3.0.CO;2-8

      Nanosized cylindrical structures consisting of a SiC core and a crosslinked polysilane coating (see Figure and also inside front cover) are produced here by ion beam irradiation of a polysilane film. It is shown that both the radius and length of the nanowires can be controlled by altering the incident ion beam, molecular weight of the polymer, and thickness of the target film.

    3. J-Aggregates Granting Giant Second-Order NLO Responses in Self-Assembled Hybrid Inorganic–Organic Materials (pages 1665–1668)

      E. Cariati, R. Ugo, F. Cariati, D. Roberto, N. Masciocchi, S. Galli and A. Sironi

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1665::AID-ADMA1665>3.0.CO;2-X

      Huge second harmonic generation (SHG) activityis displayed by the new hybrid inorganic–organic material [DAMS*][Cu5I6] (see Figure). Ab-initio XRPD structure determination explains this through the presence of cationic guest J-aggregates between Cu-defective anionic host CuI slabs. Thermal stability and thin-film suitability make the material technologically interesting.

    4. Side-by-Side Directed Multilayer Patterning Using Surface Templates (pages 1669–1673)

      X.-P. Jiang, S. L. Clark and P. T. Hammond

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1669::AID-ADMA1669>3.0.CO;2-9

      A method for fabricating two-component micropatterned polymer thin filmsis described, in which two different polymer systems can be laterally patterned onto a single surface. Chemically patterned surfaces are used to direct the adsorption of the polymer films through ionic and other secondary forces. The multilayers can be doped, e.g., with dyes (see Figure) and used in microdevices.

    5. Recognition Molecule Directed Interfacing Between Semiconductor Quantum Dots and Nerve Cells (pages 1673–1677)

      J. O. Winter, T. Y. Liu, B. A. Korgel and C. E. Schmidt

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1673::AID-ADMA1673>3.0.CO;2-6

      Attachment of semiconductor quantum dots to living neurons utilizing antibody and peptide recognition molecules has been achieved. It is shown that peptide recognition molecules provide nanometer-scale control over the targeting and separation distance between the quantum dot and the cell. The Figure shows a fluorescence image of CdS quantum dots attached by antibody binding to human neuroblastoma cells.

    6. Supramolecular Octupolar Self-Ordering Towards Nonlinear Optics (pages 1677–1681)

      H. Le Bozec, T. Le Bouder, O. Maury, A. Bondon, I. Ledoux, S. Deveau and J. Zyss

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1677::AID-ADMA1677>3.0.CO;2-J

      Spontaneous octupolar ordering in a dendrimer has been observed for highly nonlinear ruthenium complexes. Various oligomers containing N ruthenium-tris-bipyridine monomers have been synthesized and characterized. The quadratic nonlinear properties of supramolecular dendritic or predendritic structures are reported for N = 2, 3, and 7. The Figure shows a trimetallic metallo-polyimide chromophore.

    7. Superparamagnetic Photonic Crystals (pages 1681–1684)

      X. Xu, G. Friedman, K. D. Humfeld, S. A. Majetich and S. A. Asher

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1681::AID-ADMA1681>3.0.CO;2-G

      Photonic crystals consisting of monodisperse superparamagnetic colloidal particles have been synthesized. The particles (see Figure) are obtained by emulsion polymerization of styrene in the presence of freshly precipitated surface-modified iron oxide nanoparticles. A magnetic field self-assembles the particles and controls the diffraction wavelength and crystal parameters of the array.

    8. Core–Shell Structures Formed by the Solvent-Controlled Precipitation of Luminescent CdTe Nanocrystals on Latex Spheres (pages 1684–1687)

      I. L. Radtchenko, G. B. Sukhorukov, N. Gaponik, A. Kornowski, A. L. Rogach and H. Möhwald

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1684::AID-ADMA1684>3.0.CO;2-Z

      Uniform complete shells in one step on a time scale of minutes can be achieved by solvent-controlled precipitation of nanocrystals on the surface of colloidal particles. The thickness of the shells can be effectively controlled through the proper choice of the concentration ratio of colloidal particles serving as cores and the precipitated species. The Figure shows a TEM image of latex spheres covered by uniform shells of CdTe nanocrystals.

    9. Nanosecond Optical Limiting Property of a Novel Octanuclear Silver Cluster Complex Containing Arylselenolate Ligands (pages 1687–1690)

      C. Liu, X. Wang, Q. Gong, K. Tang, X. Jin, H. Yan and P. Cui

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1687::AID-ADMA1687>3.0.CO;2-H

      A silver complex with excellent optical limiting properties is presented by the authors (see Figure). A threshold fluence of 0.2 J cm–2 at 532 nm (2.5 times less than that of C60) and a signal suppression ability comparable to that of organic two-photon absorbers make the Ag8Se8-based complex promising for broadband optical limiting applications.

    10. Novel Blue Emitting Material with High Color Purity (pages 1690–1693)

      Y. H. Kim, D. C. Shin, S.-H. Kim, C.-H. Ko, H.-S. Yu, Y.-S. Chae and S. K. Kwon

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1690::AID-ADMA1690>3.0.CO;2-K

      A stable non-polymeric organic glass with a high glass transition temperature has been prepared and its properties are reported here. The purest blue emission so far achieved can be obtained with a non-doped, low molecular weight bis(spirobifluorenyl) anthracene derivative (see Figure). High-quality amorphous films of this compound with high morphological stability could be prepared by vapor deposition.

    11. Soft Crosslinkable Azo Polymer for Rapid Surface Relief Formation and Persistent Fixation (pages 1693–1697)

      N. Zettsu, T. Ubukata, T. Seki and K. Ichimura

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1693::AID-ADMA1693>3.0.CO;2-2

      Poly(ethylene oxide) side chains are the key structures in a novel azobenzene polymer with improved properties: firstly, they increase film fluidity, thus supporting surface relief gratings (SRGs) with Ar ion lasers, and secondly, their cross-linking with formaldehyde fixates this otherwise thermally reversible surface modification. The Figure shows an SRG-modified film of the new polymer.

    12. Synthesis of Cubic Antiferromagnetic KMnF3 Nanoparticles Using Reverse Micelles and Their Self-Assembly (pages 1697–1699)

      F. Agnoli, W. L. Zhou and C. J. O'Connor

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1697::AID-ADMA1697>3.0.CO;2-F

      Cubic antiferromagnetic nanoparticles of KMnF3 (see Figure) have been prepared and their synthesis as well as their properties are described in this communication. Small, ordered domains of about 350 nm size were obtained. The narrow size distribution provided by the reverse micelle technique allows the particles to self-assemble into a well-ordered array. Work towards bigger ordered areas is currently in progress.

    13. Heat-Induced Size Evolution of Gold Nanoparticles in the Solid State (pages 1699–1701)

      T. Teranishi, S. Hasegawa, T. Shimizu and M. Miyake

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1699::AID-ADMA1699>3.0.CO;2-3

      A simple method to manipulate the size of gold nanoparticles—involving heat treatment in the solid state—is reported by these authors. It is demonstrated that the nanoparticle size can be controlled from 3 to 10 nm by changing the heat-treatment temperature and/or the stabilizing agent in the presence of tetraoctylammonium bromide. The Figure shows 6.8 nm particles heat-treated at 190 °C.

    14. Well-Aligned Boron Nanowire Arrays (pages 1701–1704)

      L. M. Cao, Z. Zhang, L. L. Sun, C. X. Gao, M. He, Y. Q. Wang, Y. C. Li, X. Y. Zhang, G. Li, J. Zhang and W. K. Wang

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1701::AID-ADMA1701>3.0.CO;2-Q

      Vertically aligned boron nanowires in self-assembled large-scale arrays with excellent uniformity and high density have been fabricated using radio-frequency magnetron sputtering of boron and B2O3 powder onto various substrates. The nanowires thus produced are several tens of micrometers long and 20–80 nm wide, with typically platform-shaped tips (see Figure for a high-magnification SEM image).

    15. Stoichiometric Silicon Nitride/Silicon Carbide Composites from Polymeric Precursors (pages 1704–1708)

      M. Weinmann, A. Zern and F. Aldinger

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1704::AID-ADMA1704>3.0.CO;2-8

      A partially methylated highly branched polysilazane Si4N4CH9 is the first single-source precursor for stoichiometric Si3N4/SiC. Thermolysis delivers amorphous Si4N4C and H2 as the only gaseous by-product. Upon stepwise heating to 1900 °C, Si4N4C gradually crystallizes in the order α-Si3N4, β-SiC, and finally β-Si3N4, whereas at 2000 °C a fully crystalline α-Si/β-Si3N4/β-SiC composite is obtained (see Figure).

    16. Hydrogel Opals (pages 1708–1712)

      Z. Hu, X. Lu and J. Gao

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1708::AID-ADMA1708>3.0.CO;2-L

      Hydrogel opals, exhibiting striking iridescence while being soft and gelatinous, can be synthesized by covalent bonding (through crosslinkers) of self-assembled hydrogel nanoparticles, which consist of N-isopropyl-acrylamide copolymers with reactive side groups. Beyond their aesthetic value (see Figure and also cover) hydrogel opals are potentially useful as thermo- or electrochromic gel sensors.

    17. 4D-QSPR Analysis and Virtual Screening in Materials Science (pages 1713–1717)

      J. S. Duca, Y.-F. Tseng and A. J. Hopfinger

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1713::AID-ADMA1713>3.0.CO;2-C

      A useful tool to design and develop new materials comes in the form of analyzing the structure–property relationship (SPR) of the materials. The quantitative SPR paradigm provides information about molecular geometry as a function of conformational freedom, kinetics, temperature, and molecular alignment. The Figure shows one of the compounds used in this study in its grid cell space, which is the fundament of the analysis.

    18. Organic Multifunctional Spin Systems Based on Aminoxyl Radicals (pages 1719–1724)

      S. Nakatsuji

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1719::AID-ADMA1719>3.0.CO;2-D

      Novel multifunctional magnetic materials have received considerable attention over the past few years. Here recent advances in the development of organic multifunctional spin systems based on aminoxyl radicals are presented. Some efforts towards spin systems that are expected to display carrier transport properties, photo-functionality, liquid crystallinity, and pressure dependence (see Figure) are concentrated upon.

    19. Stimulated Polariton Scattering in Semiconductor Microcavities: New Physics and Potential Applications (pages 1725–1730)

      A. I. Tartakovskii, M. S. Skolnick, D. N. Krizhanovskii, V. D. Kulakovskii, R. M. Stevenson, R. Butté, J. J. Baumberg, D. M. Whittaker and J. S. Roberts

      Version of Record online: 30 OCT 2001 | DOI: 10.1002/1521-4095(200111)13:22<1725::AID-ADMA1725>3.0.CO;2-Z

      Highly efficient light sources (“polariton lasers”) and highly efficient optical parametric oscillators can potentially be fabricated on the basis of stimulated polariton scattering in semiconductor microcavities. The authors discuss both the physics behind this phenomenon, dominated by the bosonic nature of the polariton quasi-particles, and applications thereof. The new phenomena seen in this type of microcavities are based on polariton scattering to a macroscopically occupied coherent mode that is stimulated and from which coherent photons are emitted by leakage through the Bragg mirrors. The ability to manipulate and control the polariton dispersions in microcavities is shown to be a key factor underlying the new observations.

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