Advanced Materials

Cover image for Vol. 13 Issue 24

December, 2001

Volume 13, Issue 24

Pages 1839–1934

    1. Contents (pages 1839–1842)

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1839::AID-ADMA1839>3.0.CO;2-0

    2. Electrorheological Fluids (pages 1847–1857)

      T. Hao

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1847::AID-ADMA1847>3.0.CO;2-A

      Materials that switch from liquid-like to solid-like upon application of an electric field are coined electrorheological fluids. The general features and preparation of these smart materials are reviewed before recent advances in the improvement and applications (e.g., sensors, damping devices, inks) of these fluids are described. The Figure illustrates the mechanism by which such materials function.

    3. Nanoparticle-Induced Light Emission from Multi-Functionalized Silicon (pages 1859–1862)

      K. Prabhakaran, K. V. P. M. Shafi, A. Ulman and T. Ogino

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1859::AID-ADMA1859>3.0.CO;2-X

      A “plug and play” approach in which sonochemically synthesized amorphous Fe2O3 nanoparticles are incorporated onto device quality Si wafers is demonstrated. After annealing the amorphous Fe2O3 nanoparticles (see Figure) they change their properties from superparamagnetic to soft ferromagnetic. The samples exhibit multiple light emissions with wavelength that are crucial for optical fiber communications (see also inside front cover).

    4. New Charge Transfer–Type π-Conjugated Poly(aryleneethynylene) Containing Benzo[2,1,3]thiadiazole as the Electron-Accepting Unit (pages 1862–1864)

      T. Morikita, I. Yamaguchi and T. Yamamoto

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1862::AID-ADMA1862>3.0.CO;2-#

      A new charge-transfer polymer, containing a benzo[2,1,3]thiadiazole electron-accepting group and a 2,5-dihexyloxy-1,4-phenylene electron-donating group, has been synthesized via Pd-complex-catalyzed polycondensation. The polymer has a π-stacked structure in the solid state and forms spherulites. In addition, thin films of the polymer have a golden metallic luster (see Figure).

    5. Surface Recognition of Dipolar Molecules Entering Channels of the Organic Zeolite Tris(o-phenylenedioxy)cyclotriphosphazene (pages 1864–1867)

      T. Hertzsch, S. Kluge, E. Weber, F. Budde and J. Hulliger

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1864::AID-ADMA1864>3.0.CO;2-O

      Macroscopically polar crystals of an organic zeolite, tris(o-phenylenedioxy)cyclotriphosphazene, are obtained by partial guest exchange of included THF molecules with nonlinear optical molecules, which enter the channels via a mechanism of surface recognition (4-amino-4′-nitrobiphenyl partially (left) and fully (right) stained crystals are shown in the Figure).

    6. A New Approach to Crystallization of CdSe Nanoparticles into Ordered Three-Dimensional Superlattices (pages 1868–1871)

      D. V. Talapin, E. V. Shevchenko, A. Kornowski, N. Gaponik, M. Haase, A. L. Rogach and H. Weller

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1868::AID-ADMA1868>3.0.CO;2-0

      The growth of colloidal crystals of CdSe via controlled oversaturation is reported by these authors. In individual 3D quantum dot arrays formed in this manner, individual CdSe nanocrystals play the role of building blocks—artificial atoms in the next level of hierarchy (see also cover). Two different types of crystals— irregular and perfectly faceted hexagonal (see Figure)—can be prepared, depending on the speed of nucleation.

    7. Soluble Polythiophenes with Pendant Fullerene Groups as Double Cable Materials for Photodiodes (pages 1871–1874)

      F. Zhang, M. Svensson, M. R. Andersson, M. Maggini, S. Bucella, E. Menna and O. Inganäs

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1871::AID-ADMA1871>3.0.CO;2-3

      A novel “double cable” material for photodiodes, containing both electron- and hole-transporting functional groups, is obtained by co-polymerization of thiophenes that bear a covalently linker-bound fullerene (see Figure). Even at 14 % of fullerene substitution, the order of the main polythiophene chain is not seriously disturbed.

    8. Aligned Polythiophene Micro- and Nanotubules (pages 1874–1877)

      M. Fu, Y. Zhu, R. Tan and G. Shi

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1874::AID-ADMA1874>3.0.CO;2-M

      Templated synthesis of polythiophene micro- and nanotubules using an alumina membrane is described here. Flexible polythiophene tubules up to 60 μm in length and aligned tubule/gold bilayer films (see Figure) with an area as large as 1.8 cm2 can be obtained. These bilayer films show broad, strong redox responses with a capacitance 30 times that of a normal polythiophene film.

    9. Compatibility of Primary Hepatocytes with Oxidized Nanoporous Silicon (pages 1877–1880)

      V. Chin, B. E. Collins, M. J. Sailor and S. N. Bhatia

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1877::AID-ADMA1877>3.0.CO;2-4

      Porous silicon is a substrate highly compatible with living cells!Particularly after treatment of the surface with adhesive serum proteins, primary rat hepatocytes are easily attached while staying viable (shown by fluorescence microscopy with a vital dye—see Figure). Cells thus immobilized remain active even over a two week period, as their unchanged albumin and urea production reveals.

    10. Microporous Films Prepared by Spin-Coating Stable Colloidal Suspensions of Zeolites (pages 1880–1883)

      S. Mintova and T. Bein

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1880::AID-ADMA1880>3.0.CO;2-7

      A new, versatile preparation method for porous filmsby spin-coating with a stable suspension of pre-synthesized microscopic zeolite particles (see Figure) is reported by the authors. The scope of the method includes zeolite/substrate combinations inaccessible by direct growth, and preferred orientation of porous materials by deposition of non-spherical MFI-zeolite-type particles.

    11. Synthesis and Characterization of Rutile SnO2 Nanorods (pages 1883–1887)

      Y. Liu, C. Zheng, W. Wang, C. Yin and G. Wang

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1883::AID-ADMA1883>3.0.CO;2-Q

      Nanorods of SnO2 have successfully been prepared by calcining precursors that are produced in inverse microemulsions. The water/oil microemulsions used to prepare the precursors form an ideal nanostructural reactor for producing monodispersed nanoparticles, which can then decompose to form SnO2 nanorods (see Figure). The mechanism of formation of the nanorods by nucleation and growth processes is discussed.

    12. Novel Ultrasonically Assisted Templated Synthesis of Palladium and Silver Dendritic Nanostructures (pages 1887–1891)

      J. P. Xiao, Y. Xie, R. Tang, M. Chen and X. B. Tian

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1887::AID-ADMA1887>3.0.CO;2-2

      Well-defined noble metal dendritic structures (see Figure) can be synthesized with the assistance of ultrasonic waves and using a Raney nickel template, as revealed here. Interestingly, Raney nickel is demonstrated to act not only as the template but also as the reducing agent. Advantages of this method include mild reaction conditions and easy removal of the template.

    13. Optically Aligned Ferroelectric Liquid Crystals (pages 1891–1894)

      Y. Zhao and N. Paiement

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1891::AID-ADMA1891>3.0.CO;2-#

      A new orientation technique for chiral smectic C phasesof ferroelectric liquid crystals (FLCs) is presented. Suppression of the helical structure in the S*C phase is achieved by dissolving an azobenzene diacrylate monomer in the FLC host. Polymerization and irradiation with linearly polarized light are then used to accomplish both induction and stabilization of FLC alignment in the S*C phase (see Figure).

    14. Molecular Squares as Molecular Sieves: Size-Selective Transport Through Porous-Membrane-Supported Thin-Film Materials (pages 1895–1897)

      K. F. Czaplewski, J. T. Hupp and R. Q. Snurr

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1895::AID-ADMA1895>3.0.CO;2-C

      Novel molecular square membranes have been fabricated and the size-selective transport of various probe molecules through them demonstrated by the authors. Measurement of the permeabilities of various sized molecules through thin films of pyrazine and zinc-dipyridyl porphyrin molecular squares (see Figure) on polyester membrane supports have been performed.

    15. Photonic Bandgap Composites (pages 1898–1901)

      S. H. Foulger, P. Jiang, Y. Ying, A. C. Lattam, D. W. Smith Jr. and J. Ballato

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1898::AID-ADMA1898>3.0.CO;2-V

      A procedure for generating robust polymeric composites that exhibit photonic bandgap (PBG) and mechanochromic properties is presented (see Figure). The long-range order in colloidal arrays is stabilized through encapsulation in a robust and water-free matrix. These systems may be useful in optical sensors or switching applications.

    16. Author Index (pages 1903–1908)

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1903::AID-ADMA1903>3.0.CO;2-#

    17. Subject Index (pages 1909–1934)

      Article first published online: 11 DEC 2001 | DOI: 10.1002/1521-4095(200112)13:24<1909::AID-ADMA1909>3.0.CO;2-0

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