Advanced Materials

Cover image for Advanced Materials

July, 2000

Volume 12, Issue 14

Pages 1013–1078

    1. Are you reading this on screen, or in print? (page 1013)

      K. Junge and A. Muth

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1013::AID-ADMA1013>3.0.CO;2-J

      Rapid advances in computer technology have allowed internet publishing to bloom, and Advanced Materialshas now been online for 15 months through Wiley Interscience. Kornelia Junge and Andreas Muth discuss new services, the success of Wiley's Early View service, and how life is made easier by these developments. The Figure shows the Advanced Materials homepage.

    2. The Materials Science Interface at an Interdisciplinary Journal (pages 1015–1017)

      I. Osborne, P. Szuromi and J. Uppenbrink

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1015::AID-ADMA1015>3.0.CO;2-7

      Today's materials science is the archetypal interdisciplinary subject, and an increase in submissions in materials science has accordingly been observed by the editors of Science (the Figure depicts the multilayer-polymer color mirror that adorned the front cover of Science from March 31 this year). These editors present here an insight into the challenges of editing and publishing in this interdisciplinary journal.

    3. Tailor-Made Receptors by Molecular Imprinting (pages 1019–1030)

      H. Asanuma, T. Hishiya and M. Komiyama

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1019::AID-ADMA1019>3.0.CO;2-K

      Molecular recognition is becoming increasingly important in both research and industry(e.g., water purification). This review focuses on molecular imprinting with cyclodextrins—highly useful because of their hydrophilic exterior and hydrophobic cavity—including the very effective strategy adopted by the authors (see Figure): Several host species are assembled to form a tailor-made guest complex with extremely exclusive selectivity.

    4. Fabrication of Ordered Arrays of Multiple Nanodots Using Anodic Porous Alumina as an Evaporation Mask (pages 1031–1033)

      H. Masuda, K. Yasui and K. Nishio

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1031::AID-ADMA1031>3.0.CO;2-R

      Dot—or multiple dot—arrays of nanometer dimensions have applications in nanodevices. Control of the size and site of each dot is essential as variations can alter the optical or catalytic properties of the composite metal nanoparticles. A method is presented in which anodic porous alumina, a typical self-organized structure, is used as an evaporation mask for the shadow evaporation of a metal beam, enabling the spatially resolved deposition of the metal—or several different metals—at the bottom of the apertures of the mask. Each dot in the array is composed of two or three deposits of one or more metals.

    5. One-Dimensional Silicon Chain Architecture: Molecular Dot, Rope, Octopus, and Toroid (pages 1033–1036)

      K. Furukawa, K. Ebata and M. Fujiki

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1033::AID-ADMA1033>3.0.CO;2-F

      A new concept for molecular-scale wiring is presented here. The semiconducting polymer polysilane has been end-grafted to a surface using a technique whereby main-chain rigidity and density are controllable. The silicon chains were tethered to the surface by means of a covalent bond (see Figure) and 1D structures such as molecular dot, rope, and toroid were visualized using AFM (see also cover).

    6. Electronic Properties of Novel Mixed Oxidation–State Bis-Arene Chromium Nanowires Supported by a Mesoporous Niobium Oxide Host (pages 1036–1040)

      X. He, M. Trudeau and D. Antonelli

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1036::AID-ADMA1036>3.0.CO;2-Y

      A bis-arene complex as a semiconducting molecular wire is reported here for the first time. The mixed oxidation–state chromium-based wires were synthesized inside the channels of mesoporous niobium oxide (see Figure), whose recently discovered oxidizing ability was exploited to create holes in the guest, leading to the observed metallic behavior, and making the system attractive for the study of quantum confinement effects on molecular metals.

    7. Nanoscale Metal Replicas of Colloidal Crystals (pages 1040–1042)

      G. L. Egan, J.-S. Yu, C. H. Kim, S. J. Lee, R. E. Schaak and T. E. Mallouk

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1040::AID-ADMA1040>3.0.CO;2-V

      Porous metallic replicas of colloidal silica crystals have been produced by filling the spaces between the silica spheres with aqueous solutions containing salts of either Pt or Au. Subsequent reduction to the metal and removal of the template gave rise to a faithful replication of the porous structure for Pt (the Figure shows an edge) while the porous gold showed some disorder.

    8. Highly Regular Organization of Conjugated Polymer Chains via Block Copolymer Self-Assembly (pages 1042–1046)

      P. Leclère, A. Calderone, D. Marsitzky, V. Francke, Y. Geerts, K. Müllen, J. L. Brédas and R. Lazzaroni

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1042::AID-ADMA1042>3.0.CO;2-J

      Self-organized semiconducting structures can be generated by including conjugated chains in block copolymers, it is reported here. Thin films of rod–coil copolymers containing a conjugated and a non-conjugated segment show nanoribbons of the conjugated material (see Figure), indicating that this approach may open the door to an easy method for nanowire fabrication.

    9. Mobility in Polycrystalline Oligothiophene Field-Effect Transistors Dependent on Grain Size (pages 1046–1050)

      G. Horowitz and M. E. Hajlaoui

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1046::AID-ADMA1046>3.0.CO;2-W

      Organic field-effect transistors (OFETs) provide an excellent means to study transport phenomena in organic semiconductors. These authors have prepared a series of vacuum-evaporated films of sexithiophene and octithiophene (see Figure) with various grain size. Charge mobility, which increases with grain size, was found to be dependent on temperature in small grains, but practically temperature-independent in large-grain films.

    10. Confinement of CdSe Nanoparticles Inside MCM-41 (pages 1050–1055)

      H. Parala, H. Winkler, M. Kolbe, A. Wohlfart, R. A. Fischer, R. Schmechel and H. von Seggern

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1050::AID-ADMA1050>3.0.CO;2-T

      Control over spatial positioning of CdSe quantum dots(QDs) is a very important criterion for device fabrication. These authors utilize the ordered array of pores provided by the mesoporous material MCM-41 to achieve this. TEM of a single CdSe@MCM-41 particle (see Figure) shows that the hexagonally ordered mesostructure of MCM-41 is still intact after the growth of CdSe nanoparticles inside the mesopores.

    11. Photosensitive Polyimide/Silica Hybrids (pages 1055–1057)

      Z.-K. Zhu, J. Yin, F. Cao, X. Shang and Q. Lu

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1055::AID-ADMA1055>3.0.CO;2-#

      Improved performance of polymers, with respect to their mechanical and electrical properties for microelectronic applications, for example, can be obtained by introducing nanometer-size inorganic particles into the polymer matrix. The preparation and properties—particularly the photolithographic ones—of hybrids of a photosensitive polyimide (shown in the Figure) and silica are reported for the first time.

    12. Photostructuring and Consecutive Doping of an Anthracene-Containing Polymer: A New Approach Towards Conductive Patterns (pages 1058–1060)

      V. Sinigersky, K. Müllen, M. Klapper and I. Schopov

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1058::AID-ADMA1058>3.0.CO;2-I

      Producing patterns by changing the dopability of polymers is the approach presented here. The authors produced the image shown on an anthracene-based polymer film by illumination of the film through a mask, which destroys the dopability and conductivity. Exposure of the film to iodine renders the rest of the film dark and more conductive by ten orders of magnitude.

    13. Characterization of Hole Transport in a New Class of Spiro-Linked Oligotriphenylamine Compounds (pages 1060–1063)

      U. Bach, K. De Cloedt, H. Spreitzer and M. Grätzel

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1060::AID-ADMA1060>3.0.CO;2-R

      Spiro-containing organic charge transport materials such as the one shown in the Figure are investigated by these authors. Based on detailed temperature and field-dependent mobility studies it is shown that high mobility is preserved upon dimerization via the spiro center. Exceptional thermal stability of the amorphous state is also observed; this is normally only apparent in polymeric systems.

    14. Organic Reversible Switching Devices for Memory Applications (pages 1063–1066)

      D. Ma, M. Aguiar, J. A. Freire and I. A. Hümmelgen

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1063::AID-ADMA1063>3.0.CO;2-9

      Organic memories (non-optical) constitute an exception in the recent rapid growth of the literature related to organic electronic devices. Going against this trend, the authors present the electrical characteristics of switching devices based on a poly(methacrylate) derivative with pendent anthracene chromophores, MDCPAC. This material combines the excellent thin-film mechanical properties of poly(methacrylate) with anthracene's interesting electronic properties. MDCPAC is shown to have the basic properties required for binary information storage and potential for organic memory applications.

    15. Microcontact Printing of Proteins (pages 1067–1070)

      A. Bernard, J. P. Renault, B. Michel, H. R. Bosshard and E. Delamarche

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1067::AID-ADMA1067>3.0.CO;2-M

      The direct patterning of biomolecules on a solid substrate can be achieved using microcontact printing, a method that has been very successfully adopted for the precise and gentle transfer of proteins and lipid bilayers from stamp to substrate in 1 s, without loss of biological activity. The image shown was produced by the subsequent printing of two different proteins onto the same glass substrate (see also inside front cover).

    16. Panoscopic Silicon—A Material for “All” Length Scales (pages 1071–1078)

      E. Chomski and G. A. Ozin

      Version of Record online: 13 JUL 2000 | DOI: 10.1002/1521-4095(200007)12:14<1071::AID-ADMA1071>3.0.CO;2-J

      The first synthetic silicon photonic crystal has recently been fabricated by growing silicon inside the voids of a self-assembled opal template (see Figure). This and other recent research accomplishments in the fabrication and self-assembly of silicon over nanometer to micrometer length scales for applications in electronics, optoelectronics, and photonics are highlighted here.