Advanced Materials

Cover image for Vol. 17 Issue 9

May, 2005

Volume 17, Issue 9

Pages 1099–1206

    1. Cover Picture: Nanohybrid Shish-Kebabs: Periodically Functionalized Carbon Nanotubes (Adv. Mater. 9/2005)

      C. Y. Li, L. Li, W. Cai, S. L. Kodjie and K. K. Tenneti

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200590046

      Carbon nanotube (CNT)-seeded controlled polymer crystallization provides a simple yet effective means to periodically modify CNT surfaces. Both single- and multiwalled CNTs have been successfully decorated with polyethylene and nylon-6,6 (see Figure and cover), implying that it might be a generic method for CNT functionalization. By coupling crystalline polymers with functional groups, ordered multifunctionality could be realized on individual CNTs.

    2. Inside Front Cover: Nanoparticle Self-Assembly of Hierarchically Ordered Microcapsule Structures (Adv. Mater. 9/2005)

      R. K. Rana, V. S. Murthy, J. Yu and M. S. Wong

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200590047

      Microcapsules with multilayer-thick shells are synthesized by depositing negatively charged nanoparticles around cationic polyamine aggregates crosslinked by multivalent counteranions (see Figure and inside cover). Unique among hollow-sphere preparative routes, this rapid and green synthesis leads to a robust organic/inorganic hybrid structure, applies to a wide spectrum of colloidal species, and permits the non-destructive encapsulation of water-soluble compounds.

    3. Contents: Adv. Mater. 9/2005 (pages 1099–1106)

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200590042

    4. New Trends in the Use of Transition Metal–Ligand Complexes for Applications in Electroluminescent Devices (pages 1109–1121)

      E. Holder, B. M. W. Langeveld and U. S. Schubert

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200400284

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      Phosphorescent transition metal complexes for light-emitting devices like IrIII mixed ligand complexes and RuII systems are reviewed and specified (see Figure). Diverse host materials in which the phosphorescent emitters can be placed are discussed and recent synthetic developments involving different IrIII triplet emitters are highlighted. Finally, different synthetic routes leading to charged and non-charged complexes are briefly discussed.

    5. Thermomechanical High-Density Data Storage in a Metallic Material Via the Shape-Memory Effect (pages 1123–1127)

      G. A. Shaw, J. S. Trethewey, A. D. Johnson, W. J. Drugan and W. C. Crone

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200400942

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      By exploiting the shape-memory effect in NiTi, it is demonstrated for the first time that a metallic material can be used for rewriteable, thermomechanical data storage. Data are written as surface indentations by a nanoscale mechanical probe, read by a transducer, and erased by heating. A data array with a storage density of 10 Gbit in.–2 (∼ 6500 nm2 bit –1) is demonstrated (see Figure) but much higher storage densities are attainable with improved film planarity.

    6. Magnetic Nanotube Fabrication by Using Bacterial Magnetic Nanocrystals (pages 1128–1131)

      I. A. Banerjee, L. Yu, M. Shima, T. Yoshino, H. Takeyama, T. Matsunaga and H. Matsui

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200400724

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      Alignment of magnetic nanoparticles in nanotubes (see Figure) is produced using magnetic bacteria. The protein- and lipid-coated nanocrystals are extracted from the bacteria, and then introduced into peptide nanotubes where they are anchored by hydrogen bonding. The aligned nanoparticles behave as magnetic nanowires, with enhanced properties over unaligned magnetic nanocrystals.

    7. Whispering-Gallery-Mode Lasing from a Semiconductor Nanocrystal/Microsphere Resonator Composite (pages 1131–1136)

      P. T. Snee, Y. Chan, D. G. Nocera and M. G. Bawendi

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/adma.200401571

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      Spherical whispering-gallery-mode lasers employing CdSe/ZnS semiconductor nanocrystals (see Figure, inset scale bar: 15 μm) are assembled on a substrate using a simple, robust spin-coating fabrication method. The flexibility to choose the size of the microsphere template and the emission wavelength allows for the observation of single-mode lasing. At higher excitation intensities, lasing from higher multiexcitonic states is also observed.

    8. An Oriented Nanoporous Membrane Prepared by Pulsed Laser Deposition (pages 1136–1140)

      B. N. Nair, T. Suzuki, Y. Yoshino, S. Gopalakrishnan, T. Sugawara, S.-I. Nakao and H. Taguchi

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401294

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      Porous membranes with oriented pore structures are produced by pulsed laser deposition. The membranes, consisting of uniform nanoparticles and nanometer-sized channels 30 nm in diameter, could be subsequently coated with a denser membrane structure (falsely colored pink in Figure); these structures could be candidates for applications in separations, fuel cells, and microelectronics.

    9. Structurally Ordered Polythiophene Nanoparticles for High-Performance Organic Thin-Film Transistors (pages 1141–1144)

      B. S. Ong, Y. Wu, P. Liu and S. Gardner

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401660

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      Structurally ordered organic semiconductor nanoparticles, which form a stable nanoparticle dispersion in an appropriate liquid, are generated from regioregular poly(3,3‴-didodecylquarterthiophene) (PQT-12). This dispersion enables facile solution fabrication of high-performance semiconductor layers composed of extensive crystalline domains of lamellar π–π stacks (see Figure), yielding organic thin-film transistors with excellent field-effect-transistor properties.

    10. Nanoparticle Self-Assembly of Hierarchically Ordered Microcapsule Structures (pages 1145–1150)

      R. K. Rana, V. S. Murthy, J. Yu and M. S. Wong

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401612

      Thumbnail image of graphical abstract

      Microcapsules with multilayer-thick shells are synthesized by depositing negatively charged nanoparticles around cationic polyamine aggregates crosslinked by multivalent counteranions (see Figure and inside cover). Unique among hollow-sphere preparative routes, this rapid and green synthesis leads to a robust organic/inorganic hybrid structure, applies to a wide spectrum of colloidal species, and permits the non-destructive encapsulation of water-soluble compounds.

    11. Cholesteric Emulsions for Colored Displays (pages 1150–1152)

      G. De Filpo, F. P. Nicoletta and G. Chidichimo

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401912

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      A new colored electro-optical film obtained by means of an oriented cholesteric liquid crystal (LC) confined in droplets dispersed in an organic-monomer matrix is presented. The cholesteric LC pitch can be adjusted using a photosensitive chiral material in order to produce the three primary reflected colors (see Figure). Morphology, response times (τON and τOFF), and reflection spectra of such films are reported.

    12. Fully Functionalized High-Dielectric-Constant Nanophase Polymers with High Electromechanical Response (pages 1153–1158)

      C. Huang and Q.-M. Zhang

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401161

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      Fully functionalized nanophase polymers where high-dielectric-constant oligomers and electrically conductive oligomers are grafted to a dielectric elastomer backbone (see Figure) produce a significantly enhanced interface effect through exchange coupling. Consequently, they offer a high dielectric constant (close to 1000 at 20 Hz), an improved breakdown field and better mechanical properties, and a high electromechanical response.

    13. Polyisobutylene-block-Poly(ethylene oxide) for Robust Templating of Highly Ordered Mesoporous Materials (pages 1158–1162)

      M. Groenewolt, T. Brezesinski, H. Schlaad, M. Antonietti, P. W. Groh and B. Iván

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401549

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      Robust self-assembly with very high order is demonstrated by polyisobutylene-block-poly(ethylene oxide) (PIB–PEO) copolymers tailor-made by combining living cationic and anionic polymerization. A cubic micellar phase with long-range order and a glassy phase consisting of deformed spheroids are identified. Application of PIB–PEO in the synthesis of porous titanium oxide yields perfect anatase crystalline films with high regularity (see Figure).

    14. Nanoporous Thin Films from Self-Assembled Metallo- Supramolecular Block Copolymers (pages 1162–1165)

      C.-A. Fustin, B. G. G. Lohmeijer, A.-S. Duwez, A. M. Jonas, U. S. Schubert and J.-F. Gohy

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200402073

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      Nanoporous thin polymer films have been produced by a simple two-step approach using metallo-supramolecular block copolymers as the starting materials. The first step is the self-assembly of the copolymer, yielding cylindrical microdomains oriented normal to the substrate. The second step involves the opening of the metal–ligand complex located at the junction of the two blocks by redox chemistry to release the minor block and create the pores (see Figure).

    15. Optical Recording Materials Based on Photoisomerization of Guest Molecules of a Polymeric Crystalline Host Phase (pages 1166–1168)

      P. Stegmaier, A. De Girolamo Del Mauro, V. Venditto and G. Guerra

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401592

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      Norbornadiene (N) is used as an isolated guest in a host (the crystalline phase of robust syndiotactic polystyrene polymer films) and its valence photoisomerization to quadricyclane (Q) in it has been achieved. The product maintains the positional and orientational order of the reactant with respect to the polymeric crystallographic axes (see Figure).This system could be suitable for making molecular-sized units in optical data storage systems.

    16. Electrically Rewritable Memory Cells from Poly(3-hexylthiophene) Schottky Diodes (pages 1169–1173)

      J. H. A. Smits, S. C.  J. Meskers, R. A. J. Janssen, A. W. Marsman and D. M. de Leeuw

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401534

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      Rewritable plastic memory cells are made from polythiophene doped with inorganic salts and a plasticizer. The memory can be written and erased at ±6 V (see Figure) and read out is non-destructive. The retention time at zero bias is on the order of several minutes.

    17. Van der Waals' Condensation of ZnSe on Layered GaSe van der Waals' Surfaces: A New Route to Self-Organized Well-Defined Quantum Dot Structures (pages 1173–1177)

      E. Wisotzki, A. Klein and W. Jaegermann

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401562

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      Well-defined ZnSe nanocrystallites are formed on the van der Waals' surface of a layered semiconductor, GaSe, during deposition at elevated temperatures (see Figure). This growth process—termed van der Waals' condensation—is governed by a quasi-two-dimensional nucleation and growth made possible by the extremely weak substrate–cluster interaction.

    18. Self-Rolled Polymer and Composite Polymer/Metal Micro- and Nanotubes with Patterned Inner Walls (pages 1177–1182)

      V. Luchnikov, O. Sydorenko and M. Stamm

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401836

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      Micro- and nanotubes with interior patterns (see Figure) are fabricated by self-rolling of thin poly(4-vinylpyridine)/polystyrene bilayer films. The bending moment in the film arises from selective swelling of the crosslinked poly(4-vinylpyridine) layer in acidic water. Composite polymer/metal tubes are produced by magnetron sputtering of gold onto the top of the polymer film. The interiors of the tubes are patterned by microcontact printing patterns onto the polymer bilayer films prior to rolling.

    19. Polymeric Nanonozzle Array Fabricated by Sacrificial Template Imprinting (pages 1182–1186)

      S. Wang, C. Zeng, S. Lai, Y.-J. Juang, Y. Yang and L. J. Lee

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401117

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      Polymer nanonozzle arrays are fabricated using a sacrificial template imprinting (STI) approach (see Figure). Polymer sacrificial templates, which can be easily removed after molding, are used in place of rigid masters. This approach avoids generation of structural damage or defects during demolding. The diameter of the sharp end of each nanonozzle is as small as 80 nm, and can be further reduced by silica synthesis on the inner channel surface.

    20. Very Low Conductivity Threshold in Bulk Isotropic Single-Walled Carbon Nanotube–Epoxy Composites (pages 1186–1191)

      M. B. Bryning, M. F. Islam, J. M. Kikkawa and A. G. Yodh

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401649

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      Electrical conductivity of single-walled carbon nanotube (SWNT)–epoxy composites (see Figure) is investigated as a function of SWNT concentration, mean length, and aggregation. The composites exhibit a percolation-like conductivity with threshold volume fractions as low as 5.2 × 10–5. These low thresholds are attributed to continuous nanotube chains that form in the semi-dilute concentration regime; higher thresholds result when aggregation is inhibited.

    21. Phthalocyanine Composites as High-Mobility Semiconductors for Organic Thin-Film Transistors (pages 1191–1193)

      J. Zhang, H. Wang, X. Yan, J. Wang, J. Shi and D. Yan

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401113

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      A new class of organic semiconductors based on composites of copper phthalocyanine and nickel phthalocyanine for use in organic thin-film transistors show relatively high mobilities. X-ray diffraction of the composite films, which consist of homogenously sized crystals (see Figure), indicates the presence of a new crystalline phase incorporating both copper and nickel phthalocyanine molecules.

    22. Vesicle-Based Rechargeable Batteries (pages 1194–1198)

      I. Stanish, D. A. Lowy, C.-W. Hung and A. Singh

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401132

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      Vesicle-based rechargeable batteries can be fabricated by mounting polymerized vesicles filled with ferrocyanide or ferricyanide to a conductive surface (see Figure). The potential can be adjusted by changing the concentration ratio of hydroquinone and benzoquinone bound to the vesicle membranes. These batteries show promise as a means of supplying portable power for future autonomous nanosystems.

    23. Nanohybrid Shish-Kebabs: Periodically Functionalized Carbon Nanotubes (pages 1198–1202)

      C. Y. Li, L. Li, W. Cai, S. L. Kodjie and K. K. Tenneti

      Version of Record online: 25 APR 2005 | DOI: 10.1002/adma.200401977

      Thumbnail image of graphical abstract

      Carbon nanotube (CNT)-seeded controlled polymer crystallization provides a simple yet effective means to periodically modify CNT surfaces. Both single- and multiwalled CNTs have been successfully decorated with polyethylene and nylon-6,6 (see Figure and cover), implying that it might be a generic method for CNT functionalization. By coupling crystalline polymers with functional groups, ordered multifunctionality could be realized on individual CNTs.

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