Advanced Materials

Cover image for Advanced Materials

April 1993

Volume 5, Issue 4

Pages 242–317

  1. Masthead

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Materials Forum
    6. Communications
    7. Research News
    8. Book Reviews
    1. Masthead (page 242)

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050401

  2. Essay

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Materials Forum
    6. Communications
    7. Research News
    8. Book Reviews
    1. Electronic publishing—a question of quality (pages 243–245)

      Dr. Philip Hastings

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050402

      Radical changes in publishing are expected in the next decade due to the acceptance and accessibility of electronic media. With the advent of powerful networks such as SuperJANET, a vast quantity of data becomes available to the scientist. Perhaps the most difficult challenges presenting themselves to the scientific community are the maintenance of quality for the benefit of users, copyright for the benefit of authors and publishers, and security of information for everyone.

  3. Reviews

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Materials Forum
    6. Communications
    7. Research News
    8. Book Reviews
    1. Review of Polymer Synthesis in 1992 (pages 246–253)

      Prof. Arnulf-Dieter Schlüter

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050403

      Progress in polymer synthesis made last year is summarized in the first of three reviews in this issue on polymer science in 1992. Emphasis is placed on anionic polymerization, where much happened. Developments in other very different and less extensive areas are presented as well, for example in polyrotaxane synthesis (see Figure), with the synthesis of polymers with new types of molecular structures being preferentially treated.

    2. Polymeric materials: A review of progress in 1992 (pages 254–259)

      Dr. Wolfgang H. Meyer

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050404

      Developments in polymeric materials in 1992 were characterized by small but important steps achieved as the result of much detailed work. Increasing attention is being paid to the supramolecular structure of the materials with the aim of producing ever smaller well-defined systems. Examples cited in the review include the use of well-defined dispersions of conducting polymers, liquid crystalline polymers, nanostructured polymer alloys and composites to make materials with better processing characteristics and greater chemical or physical stability.

    3. Review of Polymer Physics 1992 (pages 260–267)

      Dr. Bernd Ewen

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050405

      Advances in polymer physics are discussed, including the latest insights into the morphology of polymeric systems, small-angle X-ray studies of liquid-crystalline polymers, and the influence of chain branching on the thermodynamic and hydrodynamic properties of polymer solutions and melts. Among the newly developed or adapted methods, NMR imaging can be used to calculate the stress distribution in a test strip of polymer, as shown in the Figure.

  4. Materials Forum

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Materials Forum
    6. Communications
    7. Research News
    8. Book Reviews
    1. Materials Forum (pages 267–306)

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050406

  5. Communications

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Materials Forum
    6. Communications
    7. Research News
    8. Book Reviews
    1. A new fluorescence probe for network formation with interesting nonlinear optical properties (pages 268–270)

      Dr. Vera Bollaert, Prof. Frans C. De Schryver, Dr. Peter Tackx, Prof. André Persoons, Dr. Jan Jaap H. Nusselder and Prof. Jos Put

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050407

      Molecular sensors can be used to monitor the polymerization of linear precursors and also the formation of epoxy networks. The synthesis and properties of a novel fluorescence probe, tris(p-isocyanatophenyl)amine (TIPA), which acts both as a crosslinking site and as a chemical sensor, are described. A dramatic change of fluorescence intensity coupled with the high second-order hyperpolarizability of TIPA and its urethane derivative make it promising for the synthesis of nonlinear optical thermosets whose degree of curing and the mobility of the crosslink points can be measured by luminescence.

    2. Optical second-harmonic effect of sol–gel inorganic–organic nanocomposites (pages 270–273)

      Dr. Lothar Kador, Dr. Reiner Fischer, Dr. Dietrich Haarer, Dr. Reiner Kasemann, Stefan Brück, Prof. Helmut Schmidt and Dr. Heinz Dürr

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050408

      Second-order nonlinear optically (NLO) active materials have promising technical applications in optoelectronic devices. A general problem in NLO-active polymeric systems is the decay of orientational order with time. Results are presented which show that using inorganic–organic composite materials produced by the sol–gel process as a rigid matrix for oriented χ(2) chromophores (Figure) may provide a means of overcoming this problem.

    3. A new technique for characterizing the porous structure of materials: Standard porosimetry of polyaniline emeraldine salts and bases (pages 274–276)

      Dr. Yuril M. Volf'kovich, Dr. Tamara K. Zolotova, Dr. Michael D. Levi and Dr. Yakov A. Letuchy

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050409

      Standard porosimetry is a new technique for measuring the pore radius distribution in microporous materials. Comparison of the porous structure parameters obtained by this technique and by gas adsorption measurements and SEM, both established methods, on polyaniline emeraldine salts and bases demonstrates that standard porosimetry can be used for the characterization of the porous structure of powders of conductive polymers and that this novel method has several advantages.

    4. Sensors for organic solvent detection in the ppm range based on dioxo[6.1.6.1]paracyclophanes—from molecular modeling to analyte recognition (pages 277–279)

      Prof. Franz L. Dickert, Alexander Haunschild, Martin Reif and Wolf-E. Bulst

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050410

      Hydrophobic coatings for mass-sensitive sensor devices, which yield a negligible water cross sensitivity, are the aim of the reported research. Molecular modeling was used to gain an understanding of the binding mechanism of some solvent molecules with a tetraazaparacyclophane containing alkyl substituents at the amino bridgeheads (CPO44VAL)— the figure shows the calculated geometry of the benzene complex of CPO44VAL. The theoretical results were then compared with the actual performance of CPO44VAL in devices.

    5. Geometry-induced charge localization in doped phenylene chains (pages 279–281)

      Heike Gregorius, Prof. Walter Heitz and Prof. Klaus Müllen

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050411

      The mechanism of charge delocalization in mono- and dianions of differently substituted oligo(p-phenylenes) has been studied by absorption spectroscopy. (Polyp-phenylene) is of great interest in this respect, but is experimentally inaccessible because of its complete insolubility and infusibility, so data on more soluble oligomeric systems that are structurally related to the polymer have to be used to extrapolate towards the behavior of the polymer. Results from UV/vis/NIR spectra and cyclic voltammetry are reported that allow the influence of substituents on the conjugation length to be reliably predicted.

    6. Novel cable shielding materials based on the impregnation of microporous membranes with inherently conducting polymers (pages 281–283)

      Dr. Poopathy Kathirgamanathan

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050412

      Cables are shielded from electromagnetic interference by wrapping them in conductive tapes such as aluminum polyester laminates, μ-metals, or metal-coated non-wovens. Inherently conducting polymer (ICP) based tapes would be a lightweight option, but these are difficult to produce continuously in large quantities. This problem can be overcome by impregnating commercially available microporous membranes with an ICP. The production and electrical characterization of such impregnated membranes, including shielding efficiency measurements, are reported.

    7. First tetrathiafulvalene (TTF) cation-radical salt containing the inorganic polyoxometalate β-[Mo8O26]4 (pages 283–285)

      Dr. Carlos J. Gómez-García, Prof. Eugenio Coronado, Dr. Smaïl Triki, Dr. Lahcène Ouahab and Dr. Pierre Delhaes

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050413

      Polyoxometalate complexes are attractive precursors for the preparation of new radical-ion salts based on π-electron organic donors of the tetrathiafulvalene (TTF) type, the most widely used molecules in the synthesis of organic conductors and superconductors. The well-defined sizes and shapes of polyoxometalates, as well as their ability to undergo multiple electron reduction, may induce novel structural and electronic properties in the organic component. The preparation and the X-ray crystal structure analysis of the new compound (TTF)7Mo8O26 are presented.

  6. Research News

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Materials Forum
    6. Communications
    7. Research News
    8. Book Reviews
    1. Capped nanometer silicon electronic materials (pages 286–288)

      Dr. Louis Brus

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050414

      New properties, structures, and concepts in solid silicon materials have been glimpsed in several experiments. In addition to the recent systematic effort to use organometallic chemical methods to make and characterize free-standing “capped” crystallites or quantum dots—the figure shows one structure of a capped polysilyne oligomer–new chemical approaches to capped nanometer silicon micelles, puckered sheets, clusters and crystallites are presented.

    2. Applications of the 1,3-dithiole unit in a post-TTF era (pages 288–292)

      Dr. Thomas K. Hansen and Prof. Jan Becher

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050415

      The versatile 1,3-dithiole (DT) ring system probably holds the record among heterocyclic systems for the most widespread use in modern materials science. Interest in derivatives of DT and the 1,3-dithiolium cation DT⊕ was boosted in the past by the discovery of metal-like conductivity in the charge-transfer complex TTF–TCNQ and superconductivity in cation radical salts of TMTSF and BEDT–TTF. The authors examine some of the new functionalized π-donor systems based on the TTF framework and comment on possible applications as sensors, molecular shuttles, organic ferromagnets and electroactive Langmuir–Blodgett films.

    3. Advances in negative Poisson's ratio materials (pages 293–296)

      Prof. Roderic Lakes

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050416

      Solids that become fatter in cross-section when stretched are rare, but do exist. How such materials—which have a negative Poisson's ratio—can be created with specific properties, the implications of these unusual properties, and recent advances are discussed. The Figure shows an example of a negative Poisson's ratio structure with mechanical isotropy in two dimensions: the laminate of Milton.

    4. An “omega” energy filtering TEM— Principles and applications (pages 297–300)

      Dr. Wolfgang Probst, Dr. Gerd Benner, Dr. Johannes Bihr and Dr. Eugen Weimer

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050417

      An energy filtering transmission electron microscope (EFTEM) has the advantage that, unlike a conventional TEM, it can also utilize the spectroscopic information carried by inelastically scattered electrons, thus making optimum use of all the available information. The design of an EFTEM featuring an Ω-type imaging electron-energy-loss spectrometer that is integrated into the imaging beam path is described, and its modes of use and possible applications discussed.

    5. Dissipative structure formation in colloidal systems (pages 300–305)

      Dr. Bernhard Wessling

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19930050418

      Self-organization phenomena are observed in most real systems. Is this true also for colloidal or microemulsion systems? It is argued that the current general practice of assuming that polymeric and non-polymeric colloidal systems are in equilibrium is not valid and that non-equilibrium thermodynamics should be applied. Photon correlation spectroscopy experiments on polyaniline dispersions are considered to indicate the presence of elongated structures (Figure).

  7. Book Reviews

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

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