Advanced Materials

Cover image for Advanced Materials

May 1996

Volume 8, Issue 5

Pages fmi–fmi, 381–454

  1. Masthead

    1. Top of page
    2. Masthead
    3. Essay
    4. Review
    5. Communications
    6. Materials Forum
    7. Articles
    8. Research News
    9. Book Reviews
    1. Masthead (page fmi)

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080501

  2. Essay

    1. Top of page
    2. Masthead
    3. Essay
    4. Review
    5. Communications
    6. Materials Forum
    7. Articles
    8. Research News
    9. Book Reviews
    1. The CNRS and materials science policy in France (pages 381–384)

      Dr. Gérard Beck

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080502

      An interdisciplinary program for materials science in France was established by the CNRS—the body responsible for basic scientific research—in 1982. The unity and coherence of materials science policy and the need to break down the barriers between traditional subjects were emphasized in 1994, when DIMAT, the interdepartmental delegation for materials science, was set up. Gérard Beck, who heads DIMAT, describes its aims, how it works, and its relationship with the CNRS.

  3. Review

    1. Top of page
    2. Masthead
    3. Essay
    4. Review
    5. Communications
    6. Materials Forum
    7. Articles
    8. Research News
    9. Book Reviews
    1. Cascading of Second-Order Nonlinearities in Polar Materials (pages 385–397)

      Dr. Christian Bosshard

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080503

      The combination of two second-order nonlinear optical (NLO) processes, termed cascading, can induce third-order nonlinearities, which are of major interest for all-optical signal processing. The concept of cascading and the basic ideas behind it are explained and some of the molecules of greatest potential in this area (e.g., DANPH, see Figure) introduced. Methods for determining cascaded nonlinearities, effects based on cascaded processes, and materials considerations are also reviewed.

  4. Communications

    1. Top of page
    2. Masthead
    3. Essay
    4. Review
    5. Communications
    6. Materials Forum
    7. Articles
    8. Research News
    9. Book Reviews
    1. Regeneration, derivatization and utilization of cellulose in ultrathin films (pages 399–402)

      Prof. Gerhard Wegner, Dr. Vera Buchholz, Prof. Lars Ödberg and Dr. Sara Stemme

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080504

      Cellulose films obtained from TISC Langmuir–Blodgett films provide a model system for adsorption studies of dyes and polyelectrolytes. The conversion of multilayers of trimethylsilylcellulose (TMSC), a “hairy-rod” molecule with short hydrophobic TMS side groups, into ultrathin cellulose films, the derivatization of these films with succinic anhydride, and the use of regenerated and modified cellulose films for adsorption studies are reported with the aim of finding ways of changing the chemical properties of cellulose films.

    2. Cooperative proton-electron transfer in a supramolecular structure of meso-1,2-bis-(4-dimethylaminophenyl)-1,2-ethanediol and bis(4-cyanobenzylidene)ethylenediamine (pages 402–405)

      Dr. Michael Felderhoff, Dr. Ingo Steller, Dr. Alicia Reyes-Arellano, Prof. Roland Boese and Prof. Reiner Sustmann

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080505

      A supramolecular 1:1 complex of the title compounds undergoes light-induced cooperative proton-electron transfer which can be switched back by warming to 60°C. The complex (see Figure) is found to exhibit a unique from the photochromism, meaning that it could have potential in optical switching (with termal back switching) or optical data storage applications.

    3. Patterning of poly(3-octylthiophene) conducting polymer films by electron beam exposure (pages 405–408)

      Dr. S. H. Magnus Persson, Dr. Peter Dyreklev and Dr. Olle Inganäs

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080506

      Accurate patterning of a conducting polymer using electron beam lithography has been demonstrated for poly(3-octylthiophene) for line widths down to 50 nm. It also proved possible to attach very closely spaced gold electrodes, with separations down to tens of nanometers, enabling the measurement of the electron transport properties of small strips consisting of a limited number of conducting polymer chains. Information gained from these experiments will be useful in molecular electronics and possibly for single electron devices.

    4. The optical behavior of lyotropic liquid crystalline polymer gel networks: Dependence on temperature (pages 408–411)

      Dr. Arno Seeboth and Dr. Hans-Rainer Holzbauer

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080507

      Gel networks with interesting optical properties have been prepared on the basis of a highly ordered aqueous polymer lyotropic liquid crystalline phase, embedded in a thermally stable polymer network. The optical transparency changes reversibly with an increasing or decreasing temperature of a few degrees up to a contrast ratio of 85:1. Different lyotropic phases exist in close proximity in the system, for example a schlieren texture (see Figure) and a radial droplet structure.

    5. Second harmonic generation in ferroelectric liquid crystal mixtures (pages 411–414)

      Dr. Josu Ortega, Dr. César Luis Folcia, Dr. Jesús Etxebarría, M. Carmen Artal, Dr. M. Blanca Ros and Prof. José Luis Serrano

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080508

      The concentration dependence of the second harmonic generation efficiency has been analyzed in binary mixtures containing a ferroelectric liquid crystal material (W313) with high spontaneous polarization and an achiral host. It has been found that the effective nonlinear coefficient is not, in general, proportional to the mixture mole fraction, although it is linearly correlated to the spontaneous polarization. Far from the transition to the chiral smectic C phase, both quantities display te same temperature dependence.

    6. A mesogen-functionized carbosilane dendrimer: A dendritic liquid crystalline polymer (pages 414–416)

      Klaus Lorenz, Dirk Hölter, Dr. Bernd Stühn, Prof. Rolf Mülhaupt and Dr. Holger Frey

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080509

      The first dendritic liquid crystalline polymer (DLCP), consisting of a flexible, second-generation dendritic carbosilane scaffold substituted with 36 rid cyanobiphenyl groups (see Figure), has been prepared. The synthesis and characterization of the mesophase are reported as an initial approach to determining how the formation of liquid crystal phases is related to the mesogen density and the spacer length in DLCPs.

    7. Five-membered heteroaromatic hydrazone derivatives for second-order nonlinear optics (pages 416–420)

      Dr. Man Shing Wong, Urs Meier, Dr. Feng Pan, Dr. Volker Gramlich, Dr. Christian Bosshard and Prof. Peter Günter

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080510

      Highly efficient frequency conversion in crystalline organic molecules for opto-electronic applications is the aim of the investigation reported here into how various heteroatomic rings affect molecular nonlinearity. The optical properties of hydrazone derivatives with the furan or thiophene moiety as part of the conjugated core are described, and 5-(methylthio)thiophenecarboxaldehyde-4-nitrophenyl-hydrazone (MTTNPH) is demonstrated to have the properties required.

    8. Fabrication of single-mode polymeric waveguides using micromolding in capillaries (pages 420–424)

      Xiao-Mei Zhao, Alison Stoddart, Dr. Stephen P. Smith, Enoch Kim, Younan Xia, Prof. Mara Prentiss and Prof. George M. Whitesides

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080511

      Micromolding in capillaries (MIMIC) has been used to fabricate arrays of single-mode polymeric waveguides from several classes of polymeric materials (epoxies, polyrethanes, and polyacrylates) supported on Si/SiO2 substrates. Waveguides clad with polymers having slightly lower refractive indices gave single-mode output in the visible and near-infrared regions. A typical waveguide structure exhibiting single-mode behavior is shown in the Figure.

    9. Oxygen ion conductivity of platinum-impregnated stabilized zirconia in bulk and microporous materials (pages 424–427)

      Dr. Andreas Ziehfreund, Dr. Ulrich Simon and Prof. Wilhelm F. Maier

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080512

      The effect of platinum impregnation on the ionic conductivity of yttria stabilized zirconia (YSZ) has been determined using complex impedance measurements in the frequency range 101–107Hz. Ionic conductivities and the corresponding activation enthalpies are reported for the temperature range 200–600°C. Platinum agglomerated at the grain boundaries of polycrystalline samples reduces ion transport across the intergranular zone. The evaporation and recondensation of YSZ and the addition of Pt results in porous materials with improved oxygen ion conductivity.

    10. Nanocrystal gold molecules (pages 428–433)

      Prof. Robert L. Whetten, Joseph T. Khoury, Dr. Marcos M. Alvarez, Dr. Srihari Murthy, Igor Vezmar, Prof. Z. L. Wang, Prof. Peter W. Stephens, Dr. Charles L. Cleveland, Dr. W. D. Luedtke and Prof. Uzi Landman

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080513

      Gold nanocrystals passivated by self-assembled monolayers of straightchain alkylhiolate molecules have been obtained as highly purified molecular materials of high intrinsic stability. Evidence is presented for a predicted discrete sequence of energetically optimal fcc structures of a truncated octahedral morphological motif (see cover). The nanocrystal materials have a propensity to form extended superlattics, such as that in the Figure.

    11. On void fraction and the nature of porous solids (pages 434–437)

      Dr. Juan M. Garcés

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080514

      A new unified model of nanoporous materials, based on a relationship between void fraction and structure, is introduced. The reduction of the complex pore system to a single void and the dense framework components t a single dense shell is shown to help in revealing the system of organization determining the structures of materials such as zeolites, clay minerals, layered compounds, and bioinorganic solids. Examples are given that demonstrate the use of the model as a predictive tool and provide insights into previously unsolved problems.

  5. Materials Forum

    1. Top of page
    2. Masthead
    3. Essay
    4. Review
    5. Communications
    6. Materials Forum
    7. Articles
    8. Research News
    9. Book Reviews
    1. Materials Forum (pages 438–440)

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080515

  6. Articles

    1. Top of page
    2. Masthead
    3. Essay
    4. Review
    5. Communications
    6. Materials Forum
    7. Articles
    8. Research News
    9. Book Reviews
    1. Non-carbon nanotubes (pages 443–445)

      Prof. Alex Zettl

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080516

      Nanotube formation is not limited to carbon, and in fact seems to be a general feature of layered materials. The classes of new nanotubes that have been synthesized, e.g., boron-nitride-containing compounds and transition-metal dichalcogenides, are briefly reviewed. Theoretical predictions, such as the type II BC2N nanocoil, the smallest possible solenoid, point to enticing research and application opportunities, for example miniature transformers and magnetic storage or on-nanotube devices (pn junctions, etc.).

  7. Research News

    1. Top of page
    2. Masthead
    3. Essay
    4. Review
    5. Communications
    6. Materials Forum
    7. Articles
    8. Research News
    9. Book Reviews
    1. The exciton binding energy in luminescent conjugated polymers (pages 447–452)

      Prof. Jean-Luc Brédas, Prof. Jérôme Cornil and Dr. Alan J. Heeger

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080517

      Luminescence in organic conjugated polymers is considered in this article, which tries to clarify some of the issues related to the nature of the emitting species. A comparison of recent experimental and theoretical data on the exciton binding energy in luminescent poly(arylenevinylene)s, polyarylenes, and their derivatives (e.g., see Figure) leads to he conclusion that they sustain rather weakly bound polaronexitons.

  8. Book Reviews

    1. Top of page
    2. Masthead
    3. Essay
    4. Review
    5. Communications
    6. Materials Forum
    7. Articles
    8. Research News
    9. Book Reviews

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