Advanced Materials

Cover image for Advanced Materials

June 1997

Volume 9, Issue 6

Pages fmi–fmi, 457–522

  1. Masthead

    1. Top of page
    2. Masthead
    3. Articles
    4. Communications
    5. Research News
    6. Conference Calendars
    1. Masthead (page fmi)

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090601

  2. Articles

    1. Top of page
    2. Masthead
    3. Articles
    4. Communications
    5. Research News
    6. Conference Calendars
    1. Materials chemistry and thermodynamics of REBa2Cu3O7−x (pages 457–473)

      Dr. Judith L. Macmanus-Driscoll

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090602

      The first decade of oxide superconductor processing has taught us that processing purely by empirical means is unsatisfactory. The materials chemistry and thermodynamics of the REBa2Cu3O7−x (RE = rare earth) series are reviewed, and examples of how the results can lead to advances in processing are presented. Particular attention is paid to phase stability and its relationship to various processing methods, including single-crystal growth and thin-film routes. Future areas of research are high-lighted.

  3. Communications

    1. Top of page
    2. Masthead
    3. Articles
    4. Communications
    5. Research News
    6. Conference Calendars
    1. Microcontact printing and electroplating on curved substrates: Production of free-standing three-dimensional metallic microstructures (pages 475–477)

      John A. Rogers, Rebecca J. Jackman and Prof. George M. Whitesides

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090603

      Parts for microelectromechanical systems often need to be three dimensional (3D) and have sizes in the micrometer range. A novel method is described for the convenient fabrication of such 3D microstructures by means of microcontact printing, electrodeposition, and removal of the substrate. The technique is illustrated with the fabrication of structures with the form required for coronary stents (see Figure).

    2. Fabrication of glassy carbon microstructures by pyrolysis of microfabricated polymeric precursors (pages 477–480)

      Dr. Olivier J. A. Schueller, Dr. Scott T. Brittain and Prof. George M. Whitesides

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090604

      High-carbin mcirostructures as components in microelectromechanical structures and microreactors are of particular interest because their mechanical, electrical, and chemical properties can be controlled by the temperature of preparation. The range of electrical properties is especially impressive. A method of fabricating microstructures of glassy carbon and other high-carbon solids is presented, based on micromolding of polymers to form precursors to these structures and pyrolysis to yield the carbon solids. The advantages of the technique are discussed.

    3. Coupling of an induced fit enzyme to polydiacetylene thin films: Colorimetric detection of glucose (pages 481–483)

      Dr. Quan Cheng and Prof. Raymond C. Stevens

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090605

      A new biosensor design is demonstrated, in which a protein conformational change is used as a trigger mechanism for a low-cost, solid-state sensor (see also the cover). The figure illustrates the principle: an enzyme (hexokinase, large white shape) immobilized on a lipid polydiacetylene (PDA) layer undergoes a conformational change when glucose (dark shape) binds to it. The resulting stress in the PDA layer produces a color change.

    4. Conformational polymorphism of oligothiophenes: X-ray structure of the monoclinic form of 3, 3′, 4″, 3″′-Tetrakis(methylsulfany-l)2, 2′:5′, 2″:5″, 2″′-Quaterthiophene (pages 484–487)

      Dr. Giovanna Barbarella, Dr. Massimo Zambianchi, Dr. Montserrat del Fresno I Marimon, Prof. Luciano Antolini and Prof. Alessandro Bongini

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090606

      Conformational polymorphism of an oligothiophene the title compound (T4S), is reported for the first time. Efficient synthesis of T4S produced, in addition to the triclinic, deep orange crystals reported previously, a second (yellow, monoclinic) form of T4S, whose structure as revealed by single-crystal X-ray diffraction is presented here. The synthetic pathway is outlined and the molecular structure and crystal packing are discussed. The significantly different π-delocalization in the two conformations indicates the need for very careful molecular characterization.

    5. Superstructures of lipid bilayers by complexation with helical biopolymers (pages 487–490)

      Dr. Anije Wenzel and Prof. Markus Antonietti

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090607

      Polyelectrolyte–surfactant complexes have properties that may allow them to be used to replace expensive and syntehtically complicated chiral liquid-crystal systems in display applications, for example. The model systems of poly-L-lysin complexed with soybean lecithin—the Figure shows the structure model—and κ-carrageenan with various dialkyldimethylammonium salts are described.

    6. Chemical vapor deposition of thin polymer films used in polymer-based light emitting diodes (pages 490–493)

      Dr. Kathleen M. Vaeth and Prof. Klavs F. Jensen

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090608

      A chemical vapor deposition (CVD) technique for the preparation of the conjugated polymer PPV, poly(phenylenevinylene), is presented. The thin films were prepared by CVD of a chlorine precursor polymer from a dichloro-p-xylene monomer followed by a thermal conversion step. The preparation and apparatus are detailed and results of UV-vis and IR spectroscopy discussed. Spontaneous orientation of the polymer during growth is revealed, which suggests the possibility of fabricating chain-oriented polymers by CVD.

    7. Chiroptical properties of poly{2, 5-bis[(S)-2-methylbutoxy]-1, 4-phenylene vinylene} (pages 493–496)

      Emiel Peeters, Ann Delmotte, Dr. René A. J. Janssen and Prof. E. W. Meijer

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090609

      The photoluminescent and electroluminescent properties of conjugated polymers are, in part, controlled by interchain interactions in solid films. A study of the (chir)optical properties of optically active BMB-PPV (see Figure) shows that circular dichroism spectroscopy is very powerful in detecting association of the polymer. Two different forms of BMB-PPV are reported to be present in solution, depending on the solvent.

    8. Simulation of layered double hydroxide intercalates (pages 496–500)

      Dr. A. Michael Aicken, Iain S. Bell, Dr. Peter V. Coveney and Dr. William Jones

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090610

      Computational simulations of layered double hydroxides (LDHs), based on relatively simple models and simulation procedures (classically based force-field calculations), are shown to be an effective technique for rationalizing the orientation fo guest species. It is demonstrated that the simulations yield valeus for the gallery heights that agree well with those observed experimentally and that intercalculated water plays an important role. LDHs are of interest for applications in catalysis, medicine, molecular sieing, electrochemistry, and oil-field exploration.

    9. Access in mesoporous materials: Advantages of a uniform pore structure in the design of a heavy metal ion adsorbent for environmental remediation (pages 500–503)

      Dr. Louis Mercier and Prof. Thomas J. Pinnavaia

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090611

      The access of guest species to the binding sites of adsorbent determines the metal-binding capacity of materials, which is important for example in environmental remediation efforts. It is shown that MP-HMS, the mercaptopropylsilane-functionalized derivative of the molecualr sieve HMS, with its regular pore structure is a much better Hg2⊕ absorbent than silica gels, in which functionalization leads to pore blocking (see Figure).

    10. Superconducting RNi2B2C (R = Y, Lu) nanoparticles: Size effects and weak links (pages 503–506)

      Dr. Wolfgang K. Maser, Dr. Patrick Bernier, Dr. Igor Luk'yanchuk, Dr. Philippe Molinié, Prof. Serge Lefrant, Philipp Redlich and Prof. Pulickel M. Ajayan

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090612

      The potential of the are discharge technique for the growth of complex nanocrystallien systems is demonstrated here with the formation of quaternary superconducting nanoparticles belonging to the recently discovered intermetallic boron carbide family RNi2B2C (R = Y, Lu). The nanoparticles, which were embedded in a glassy carbon matrix and had Tc – 15 K, are reported to exhibit magnetic behavior characterized by finite size effects and weak Josephson links between the particles. The formation and characterization of the nanoparticles are detailed.

  4. Research News

    1. Top of page
    2. Masthead
    3. Articles
    4. Communications
    5. Research News
    6. Conference Calendars
    1. Block copolymer epitaxy (pages 509–511)

      Prof. Masahito Sano

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090613

      Polymer-induced epitaxy allows polymer epitaxy to be used not only for growth of crystalline polymers but also in techniques for functionalizing surfaces. A method is described by which it is possible to produce a crystalline polymer but also in techniques for functionalizing surfaces. A method is described by which it is possible to produce a crystalline polymer block epitaxially on a substrate with a non-crystalline block—which can later be functionalized—anchored to the crystalline block but not attached to the surface (see Figure).

    2. Interfaces and interphases of (bio)materials: Definitions, structures, and dynamics (pages 513–518)

      Prof. Kurt E. Geckeler, Frank Rupp and Dr. Jürgen Geis-Gerstorfer

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090614

      What exactly is an interface, and when is an interphase the more correct concept? The nature of interfaces and the phenomena occurring there are described before the role of interphases is illustrated with a series of examples taken from purely artificial systems (e.g., polymer and polymer-metal “interfaces”) and natural and mixed artificial–natural systems (e.g., the multilayer interphase of a biomedical system such as a dental implant). The approach presented demonstrates that “interphase” or “interface” depends to some extent on the point of view.

  5. Conference Calendars

    1. Top of page
    2. Masthead
    3. Articles
    4. Communications
    5. Research News
    6. Conference Calendars
    1. Conference Calendar (pages 519–522)

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970090615

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