Advanced Materials

Cover image for Vol. 14 Issue 21

November, 2002

Volume 14, Issue 21

Pages 1519–1589

    1. Contents: Adv. Mater. 21/2002 (pages 1519–1523)

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1519::AID-ADMA1519>3.0.CO;2-I

    2. Nanostructured Composites: A High Capacity, Fast Rate Li3V2(PO4)3/Carbon Cathode for Rechargeable Lithium Batteries (pages 1525–1528)

      H. Huang, S.-C. Yin, T. Kerr, N. Taylor and L.F. Nazar

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1525::AID-ADMA1525>3.0.CO;2-3

      Impressive capacity improvements can be obtained by wrapping insulating crystallites of Li3V2(PO4)3 within a conductive carbon web. The single crystal analysis (see Figure) and electrochemical characteristics of Li3V2(PO4)3 are reported. X-ray diffraction analysis of the single phases formed on Li extraction shows that the framework is maintained with a little loss of crystallinity; on re-insertion of Li, the Li3.0V2(PO4)3 framework is fully recrystallized.

    3. Disassembling Three-Dimensional Metallo-Dielectric Photonic Crystals into Metallic Photonic Crystal Sheets and Wires (pages 1528–1531)

      F. Li, L. Xu, W.L. Zhou, J. He, R.H. Baughman, A.A. Zakhidov and J.B. Wiley

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1528::AID-ADMA1528>3.0.CO;2-M

      Lower dimensional photonic crystals have been created from pre-formed three-dimensional photonic crystals by mechanical processing. One-dimensional photonic crystals (corrugated nanowires—see Figure), and two-dimensional metal-mesh photonic crystals of between one and fifty sheets may both be made by this process. Possible applications that could be enabled include fibrous photonic crystal colorants for plastics and 1D photonic crystal wires.

    4. Dichalcogenide Nanotube Electrodes for Li-Ion Batteries (pages 1531–1534)

      R. Dominko, D. Arčon, A. Mrzel, A. Zorko, P. Cevc, P. Venturini, M. Gaberscek, M. Remskar and D. Mihailovic

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1531::AID-ADMA1531>3.0.CO;2-P

      Large amounts of Li ions can be electrochemically intercalated into and controllably released by the channels between individual molybdenum selenide nanotubes (see Figure), forming the basis for a promising safe new battery electrode material. The use of dichalcogenide nanotubes rather than the more usual carbon is shown to have important advantages.

    5. Metallodielectric Photonic Structures Based on Polyelectrolyte Multilayers (pages 1534–1537)

      T.C. Wang, R.E. Cohen and M.F. Rubner

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1534::AID-ADMA1534>3.0.CO;2-7

      The processing of photonic structures using layer-by-layer assembly of polyelectrolytes and in-situ inorganic nanoparticle synthesis is reported. This approach facilitates the precise tuning of layer thicknesses and therefore optical response, and conformal large area coverage. Refractive index contrast of the polyelectrolyte multilayers (see Figure) is enhanced and manipulated by controlling silver nanoparticle concentration and distribution.

    6. A Simple Route for the Synthesis of Multi-Armed CdS Nanorod-Based Materials (pages 1537–1540)

      F. Gao, Q. Lu, S. Xie and D. Zhao

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1537::AID-ADMA1537>3.0.CO;2-Q

      The length of the arms of a nanorod-based architecture can be adjusted from 100 nm up to a micrometer (see Figure) when using the simple one step surfactant-ligand co-assisted solvothermal technique reported here. The arm lengths are controlled by simply changing the relative concentrations of dodecylthiol and ethylenediamine when preparing the multi-armed CdS architecture with CdCl2 and thiourea as reactants.

    7. Toughening of Polymers by Self-Assembling Molecules (pages 1540–1543)

      J.C. Stendahl, L. Li, E.R. Zubarev, Y.-R. Chen and S.I. Stupp

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1540::AID-ADMA1540>3.0.CO;2-T

      Dendron rod–coil molecules (DRCs) spontaneously assemble into birefringent gel-forming networks when added to styrene in small amounts. It is shown that DRC gel derived polystyrene (PS) has greater birefringence than the PS homopolymer when drawn under similar conditions.The dispersed DRC nanophase is responsible for a 70 % increase in impact strength over the PS homopolymer, as well as interesting fracture behavior (see Figure).

    8. Eggshell Membrane Templating of Hierarchically Ordered Macroporous Networks Composed of TiO2 Tubes (pages 1543–1546)

      D. Yang, L. Qi and J. Ma

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1543::AID-ADMA1543>3.0.CO;2-B

      Hierarchically ordered macroporous networks (see Figure) composed of TiO2 tubes made of anatase nanocrystals have been fabricated by sol–gel coating of organic eggshell membrane consisting of interwoven shell membrane fibers. The unique hierarchical structure, together with the high surface area and substantial porosity, make this material attractive for a number of applications.

    9. Synthesis and Micropatterning of Semiconducting Polypyrrole Nanofilms by a Two-Step Deposition/Polymerization Process (pages 1546–1549)

      J. Bai, C.M. Snively, W.N. Delgass and J. Lauterbach

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1546::AID-ADMA1546>3.0.CO;2-U

      Micropatterning of polypyrrole films can be achieved via vacuum deposition of monomers, followed by UV-induced selective polymerization (see Figure). This fabrication process minimizes the surface roughness by the separation of monomer deposition and subsequent polymerization. Vacuum deposition has the additional advantage of forming films that have low contamination levels and possess a well-defined thickness and morphology.

    10. Redox-Switching of Electrorefractive, Electrochromic, and Conductivity Functions of Cu2+/Polyacrylic Acid Films Associated with Electrodes (pages 1549–1553)

      V.I. Chegel, O.A. Raitman, O. Lioubashevski, Yu. Shirshov, E. Katz and I. Willner

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1549::AID-ADMA1549>3.0.CO;2-C

      A polyacrylic acid film saturated with Cu2+ ions displays redox-switchable electrorefractive, electrochromic, and conductivity functions upon reduction of Cu2+ to Cu0. Surface plasmon resonance spectroscopy, adsorption spectroscopy, and conductivity measurements are used to examine these functions, which are demonstrated to be fully reversible. New types of optical filters and modulators, optoelectronic devices, and smart windows could potentially be constructed from such hybrid polymers.

    11. Approaching Nanoxerography: The Use of Electrostatic Forces to Position Nanoparticles with 100 nm Scale Resolution (pages 1553–1557)

      H.O. Jacobs, S.A. Campbell and M.G. Steward

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1553::AID-ADMA1553>3.0.CO;2-9

      Nanoparticles have been self-assembled using a novel technique described as nanoxerography (see cover). A method has been developed by the authors to pattern charge with 100 nm resolution. These charge patterns act as “receptors” for nanoparticles (see Figure), enabling the directed self-assembly of nanoparticles from a powder, gas phase (aerosol), and liquid phase (suspension).

    12. Controllable Fabrication of Aligned Carbon Nanotubes: Selective Position and Different Lengths (pages 1557–1560)

      X.B. Wang, Y.Q. Liu, P.A. Hu, G. Yu, K. Xiao and D.B. Zhu

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1557::AID-ADMA1557>3.0.CO;2-M

      Three-dimensional (3D) aligned carbon nanotube arrays can be controllably fabricated at high resolution by pyrolysis of iron phthalocyanine under Ar/H2 at 950 °C. The difference of growth rate of the nanotubes between the catalyst region and the bare substrate surface results in formation of the 3D nanotube arrays (see Figure). This opens the way for fabricating 3D nanotube micropatterns and novel nanoelectronic devices.

    13. An Efficient Route to Graphitic Carbon-Layer-Coated Gallium Nitride Nanorods (pages 1560–1562)

      W. Han and A. Zettl

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1560::AID-ADMA1560>3.0.CO;2-P

      The coating of gallium nitride nanorods with graphitic carbon layers via conventional chemical vapor deposition is reported. The outer graphitic shells are generally composed of 1–5 layers, encapsulating GaN nanorods of diameter 5–60 nm and lengths of up to 30 μm (see Figure). These chemically inert protection layers conform to the shape of the nanorod edges, whether straight or saw-like.

    14. Protein Cage Constrained Synthesis of Ferrimagnetic Iron Oxide Nanoparticles (pages 1562–1565)

      M. Allen, D. Willits, J. Mosolf, M. Young and T. Douglas

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1562::AID-ADMA1562>3.0.CO;2-D

      Homogeneous magnetic nanoparticles can be synthesised within the constrained volume architecture of Listeria innocua (see Figure). This ferritin-like protein cage provides a limited reaction environment for the synthesis of 5 nm diameter ferrimagnetic iron oxide maghemite nanoparticles. The results suggest a new general synthesis route for nanomaterials, utilizing the inherent host–guest properties of protein cage architectures.

    15. High-Temperature Microfluidic Lithography (pages 1565–1567)

      D. Pisignano, E. Sariconi, M. Mazzeo, G. Gigli and R. Cingolani

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1565::AID-ADMA1565>3.0.CO;2-W

      Large-area polymer patterns can now be easily obtained using microfluidic lithography, under conditions that overcome the slow pattern formation inherent to this technique. The strong temperature dependence of the viscosity of the polymers employed in microfluidic lithography is exploited to increase the filling rate of the elastomeric microchannels. The throughput of high-temperature lithography in capillaries by polyurethane can be increased by up to a factor of 60 with respect to the room-temperature process. In addition, the method can be applied to any kind of substrate and a variety of liquids.

    16. A Highly Regular Two-Dimensional Array of Au Quantum Dots Deposited in a Periodically Nanoporous GaAs Epitaxial Layer (pages 1567–1570)

      G. Cheng and M. Moskovits

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1567::AID-ADMA1567>3.0.CO;2-K

      Regular, periodic nanopore arrays can be created via a process of electrochemical synthesis of highly ordered, porous anodic alumina films, which are then used as contact masks to etch a GaAs epitaxial layer (see Figure). Gold nanoparticles are then vapor deposited into the pores through the contact. The resulting structure is reminiscent of the periodic nanoparticle arrays predicted to display plasmonic bandgaps.

    17. Efficient Red-Emitting Hybrid Materials Based on Zeolites (pages 1570–1574)

      D. Sendor and U. Kynast

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1570::AID-ADMA1570>3.0.CO;2-N

      Rare earth ion-exchanged zeolites exhibit a tremendous enhancement of luminescence upon treatment with suitable organic complexing agents, as reported here. For Eu3+ exchanged zeolite X, the β-diketone 1-thienyl-4,4,4-trifluoro-1,3-butane-1,3-dione leads to the formation of intra-zeolite complexes. Fully coordinated complexes within the supercages may be obtained by the additional coordination of 1,10-phenanthroline (see Figure).

    18. High Electromechanical Responses in a Poly(vinylidene fluoride–trifluoroethylene–chlorofluoroethylene) Terpolymer (pages 1574–1577)

      F. Xia, Z.-Y. Cheng, H.S. Xu, H.F. Li, Q.M. Zhang, G.J. Kavarnos, R.Y. Ting, G. Abdul-Sadek and K.D. Belfield

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1574::AID-ADMA1574>3.0.CO;2-#

      Addition of an astutely selected third monomer to poly(vinylidene fluoride–trifluoroethylene) (P(VDF-TrFE))-based polymers can significantly improve their electromechanical response. This is demonstrated here for the terpolymer containing 1,1-chlorofluoroethylene as the third monomer, which effectively reduces the all-trans conformation in the polymer, and thus enhances the molecular conformational changes that accompany the polarization response under an external electric field.

    19. Nanostructured Thin Films via Self-Assembly of Block Copolymers (pages 1579–1583)

      G. Krausch and R. Magerle

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1579::AID-ADMA1579>3.0.CO;2-6

      A rich variety of thin-film structures arises from the self-assembly of incompatible block co- and terpolymers (see inside cover). These regular supramolecular structures have critical dimensions in the 10–100 nm regime, and some exhibit high complexity and order. The Figure shows a tapping-mode SFM image of an SBS (polystyrene/polybutadiene block copolymer) film on a silicon substrate after annealing in chloroform vapor.

    20. Perfluorocyclobutyl Copolymers for Microphotonics (pages 1585–1589)

      D.W. Smith Jr., S. Chen, S.M. Kumar, J. Ballato, C. Topping, H.V. Shah and S.H. Foulger

      Version of Record online: 4 NOV 2002 | DOI: 10.1002/1521-4095(20021104)14:21<1585::AID-ADMA1585>3.0.CO;2-S

      A unique combination of attributes ideal for photonic technologies, is enjoyed by perfluorocyclobutyl (PFCB) polymers, such as manipulable refractive indices and thermo-optic coefficients, low transmission losses, high thermal, mechanical, and optical stability, and excellent processability. PFCB structures can be processed by direct micro-transfer molding (see Figure)—a step towards soft-lithographic fabrication of polymer lightwave circuits.

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