Advanced Materials

Cover image for Advanced Materials

March, 2000

Volume 12, Issue 6

Pages 403–467

    1. Photopatterning and Visualization of Adsorbed Monolayers of Bis(1-benzyl-4-pyridinio)ethylene Moieties (pages 403–407)

      M. Nakagawa, S.-K. Oh and K. Ichimura

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<403::AID-ADMA403>3.0.CO;2-3

      No abstracts

    2. Biologically Produced Silver–Carbon Composite Materials for Optically Functional Thin-Film Coatings (pages 407–409)

      R. Joerger, T. Klaus and C. G. Granqvist

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<407::AID-ADMA407>3.0.CO;2-O

      Metal-containing bacteria as precursors for thin films is the concept behind the production of these ceramic–metal composites (cermets) that consist of an organic carbon matrix with embedded crystalline metallic silver particles of various morphologies and sizes (see Figure). It is demonstrated that the optical properties of the films can be tailored by adjustment of temperature and metal volume fraction.

    3. Thin-Film V[TCNE]x Magnets (pages 410–413)

      K. I. Pokhodnya, A. J. Epstein and J. S. Miller

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<410::AID-ADMA410>3.0.CO;2-B

      A low-temperature CVD process for thin-film magnet fabrication is reported here with a variety of rigid and flexible substrates (see also cover). These polymeric magnets have enhanced air stability with respect to those prepared from solution, and an opportunity is provided for the preparation of a broad range of patterned and multilayered magnetic structures.

    4. Microstamping of a Biological Ligand onto an Activated Polymer Surface (pages 413–417)

      Z. Yang and A. Chilkoti

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<413::AID-ADMA413>3.0.CO;2-#

      Patterning of bioligands and proteins onto surfaces has important applications in tissue engineering and biosensor fabrication, but until now the best results have utilized organic films on gold. These authors present a new method (MAPS), and demonstrate its use by micropatterning a biotin ligand onto the widely used biomaterial poly(ethylene terephthalate), shown in the Figure.

    5. Magnetic Nanoparticles Trapped in pH 7 Hydrogels as a Tool to Characterize the Properties of the Polymeric Network (pages 417–420)

      C. R. Mayer, V. Cabuil, T. Lalot and R. Thouvenot

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<417::AID-ADMA417>3.0.CO;2-K

      Hydrogels are expected to have important applications as biomaterials, while the dispersion of nanoparticles in such polymeric matrices can provide optical or electrical properties. Here is described the inclusion of Fe2O3 nanoparticles in several hydrogels. Analysis of the resulting magnetic polyacrylamide gels includes their ability to swell in aqueous solution (the Figure shows such a gel before and after swelling).

    6. Electrical Transport Through Individual Vanadium Pentoxide Nanowires (pages 420–424)

      J. Muster, G. T. Kim, V. Krstić, J. G. Park, Y. W. Park, S. Roth and M. Burghard

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<420::AID-ADMA420>3.0.CO;2-7

      The controlled deposition of individual V2O5 nanowires on chemically modified SiO2 substrates is reported here. Electrical transport measurements were performed on individual fibers (see Figure) and on thin fiber networks, and the conductivity of an individual V2O5 nanowire was estimated to be ∼0.5 S/cm at room temperature. The structure of the fibers was investigated using scanning force microscopy.

    7. Constructive Nanolithography: Site-Defined Silver Self-Assembly on Nanoelectrochemically Patterned Monolayer Templates (pages 424–429)

      R. Maoz, E. Frydman, S. R. Cohen and J. Sagiv

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<424::AID-ADMA424>3.0.CO;2-S

      Constructive nanolithography is a template-controlled self-assembly strategy that is extended here to the construction of hybrid metal–organic surface nanostructures. The Figure depicts a metallic silver island self-assembled on a top-functionalized thiosilane monolayer, the island being grown in situ from silver nanoparticles generated by tip-induced electrochemical reduction of surface-bound metal ions.

    8. Selective Functionalization of Mesoporous Silica (pages 430–432)

      F. de Juan and E. Ruiz-Hitzky

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<430::AID-ADMA430>3.0.CO;2-3

      Selective functionalization of the internal and external surfaces of MCM-41 silica has been achieved using a topochemical molecular engineering approach. Functionalization is carried out in a stepwise process, the groups becoming selectively attached via silane coupling reactions and through use of a template to produce a structure with external trimethysilyl groups and internal aryl groups (see Figure).

    9. A Ligand-Stabilized Tetrameric Zinc(II) Cluster with High-Efficiency Emission from Both Singlet and Triplet Excited States for Electroluminescent Devices (pages 433–436)

      Y. Ma, T. Lai and Y. Wu

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<433::AID-ADMA433>3.0.CO;2-S

      Blue photoluminescence with high quantum efficiency is emitted by both the singlet and triplet excited states of the 7-azaidolate-containing tetrameric zinc(II) cluster (Zn4O(AID)6) (see Figure) in solution and in the solid state at room temperature. A blue light–emitting diode with Zn4O(AID)6 as the active layer is shown to have an electroluminescence efficiency of 0.8 %.

    10. Donor Slab Robustness and Band Filling Variations in BDT–TTP-based Molecular Conductors: β-(BDT–TTP)6[Re6S6Cl8]·(CH2Cl–CHCl2)2 and β-(BDT–TTP)6 [Mo6Cl14]·(CH2Cl–CHCl2)2 (pages 436–439)

      A. Deluzet, P. Batail, Y. Misaki, P. Auban-Senzier and E. Canadell

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<436::AID-ADMA436>3.0.CO;2-G

      Two new phases for the metallic salts based on 2,5-bis(1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalene have been prepared and shown to exhibit metallic conductivity down to low temperature. The organic slab topology and band structure are identical to previously determined 2:1 salts of the same donor with smaller monoanions—only the Fermi surface (see Figure) is modified by changing the anion volume and charge.

    11. Nanocrystalline MgAl2O4: Measurement of Thermodynamic Properties Using a Solid State Cell (pages 440–444)

      K. T. Jacob, K. P. Jayadevan, R. M. Mallya and Y. Waseda

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<440::AID-ADMA440>3.0.CO;2-#

      The tremendous enhancement of the physical, chemical, and mechanical propertiesof materials in their nanocrystalline state is being exploited in a number of frontier technologies; however, concern in the use of nanocrystalline materials is their stability during high-temperature exposure, either while processing or in service. Reported in this communication is a new solid-state electrochemical method for the accurate determination of high-temperature surface thermodynamic properties of nanocrystalline ceramics, using MgAl2O4 as a model compound.

    12. Fabrication of a Nanostructured Diamond Honeycomb Film (pages 444–447)

      H. Masuda, M. Watanabe, K. Yasui, D. Tryk, T. Rao and A. Fujishima

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<444::AID-ADMA444>3.0.CO;2-K

      Micromechanical and electronic devices are a potential application for nanohoneycomb-structured diamond films, which were produced by oxygen plasma etching with porous anodic alumina films as masks to give highly ordered hexagonal hole arrays with high aspect ratios. The high refractive index and high transparency of these structures make them suitable for photonic bandgap materials.

    13. Modification of TiO2 Heterojunctions with Benzoic Acid Derivatives in Hybrid Molecular Solid-State Devices (pages 447–451)

      J. Krüger, U. Bach and M. Grätzel

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<447::AID-ADMA447>3.0.CO;2-8

      Control of semiconductor device performance has been investigated by introduction of a series of organic molecule layers at the heterojunction between TiO2 and the p-type semiconductor spiro-MeOTAD (see Figure). The variation of the current–voltage characteristics of these devices, as well as the change in the workfunction of the molecules' modified TiO2 surfaces can be correlated with the molecules' dipole moments.

    14. Preparation of Y2O3:Eu Phosphor Particles of Filled Morphology at High Precursor Concentrations by Spray Pyrolysis (pages 451–453)

      Y. C. Kang, H. S. Roh and S. B. Park

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<451::AID-ADMA451>3.0.CO;2-S

      Control over the morphology of Y2O3:Eu phosphor particles has been achieved using colloidal seed-assisted spray pyrolysis, with yttrium and gadolinium hydroxy carbonate sols as nucleation seeds. These particles, which have important applications in display technology, showed spherical and filled morphology (see Figure) before and after post-treatment.

    15. Hybrid Biomaterials for Tissue Engineering: A Preparative Method for PLA or PLGA–Collagen Hybrid Sponges (pages 455–457)

      G. Chen, T. Ushida and T. Tateishi

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<455::AID-ADMA455>3.0.CO;2-C

      A novel hybrid biomaterial for tissue engineeringhas been developed by forming collagen microsponges in the pores of poly(alpha ester) sponge. Poly(alpha ester) sponge provides the skeleton with a high degree of mechanical strength, while the collagen provides cell compatibility. The Figure shows mouse fibroblast cells and bovine articular chondrocytes adhered to a PLGA–collagen hybrid sponge.

    16. Liquid Crystal–Based Photonic Devices: LC Photonet (pages 459–467)

      G. Abbate and J. M. Otón

      Version of Record online: 3 MAR 2000 | DOI: 10.1002/(SICI)1521-4095(200003)12:6<459::AID-ADMA459>3.0.CO;2-X

      LC Photonet is a network of collaborators from industry and academia across Europe committed to addressing problems that need to be solved in liquid crystal (LC) research for the realization of optical and electro-optical devices. This report introduces LC Photonet and presents its major research activities—integrated optics, large-area optical devices, ferroelectric LC devices, and chemistry and new materials—as well as recent results.